Sitecore :- How to update build data through excel sheet, How to create template through code, How to add formating to HTML

using Sitecore.Data.Items;
using BusinessModules;
using Sitecore.Data.Fields;
using System.Text.RegularExpressions;
using System.Text;
using Sitecore.Data.Managers;
using Sitecore.Security.Accounts;
using System.Data.OleDb;
using HtmlAgilityPack;
using System.Text.RegularExpressions;
using System.IO;
using System.Xml;
namespace ABC.layouts
{
   
    public partial class ScriptsOnDemand : System.Web.UI.Page
    {
        private void Import()
        {
            Sitecore.Data.Database master = Sitecore.Configuration.Factory.GetDatabase("master", false);
            OleDbCommand command = null;
            string con = string.Empty;

            //connString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + strNewPath + ";Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=2\"";
            con = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\EpicCV.xls;Extended Properties='Excel 4.0;HDR=Yes;'";

            try
            {
                Sitecore.Data.Items.Item rootItem = master.GetItem("/sitecore/content/Global Content/People/A");

                List BiosItem = new List(rootItem.Axes.GetDescendants().Where(m => m.TemplateID.ToString() == "{EB65BFA3-5122-43F4-A1B0-02F430F645CA}"));

                StringBuilder sb = new StringBuilder();

                using (OleDbConnection connection = new OleDbConnection(con))
                {
                    connection.Open();
                    command = new OleDbCommand("select * from [Report1$]", connection);
                    sb.Append("");
                   
                    sb.Append(" ");
                    using (OleDbDataReader dr = command.ExecuteReader())
                    {
                        int counter = 0;
                        while (dr.Read())
                        {
                            counter = counter + 1;

                            string emailID = dr["BusinessEmail"].ToString().Trim();
                            string bioVersionName = bioVersionName = dr["lastName"].ToString().Trim() + " " + dr["FirstName"].ToString().Trim();
                            string mainBiographyNarrative = formatHTML(  dr["Bio Narrative"].ToString().Trim() );
                            string experienceNarrative = formatHTML( dr["Experience Narrative"].ToString().Trim());

                            List itemMainBioList = BiosItem.Where(x => x.Fields["Email"].ToString() == emailID).ToList();
                            foreach (Item itemMainBio in itemMainBioList)
                            {
                                sb.Append(" ");
                                sb.Append(" ");
                                if (!String.IsNullOrEmpty(emailID))
                                {
                                    sb.Append(" ");
                                }
                                try
                                {
                                    if (itemMainBio.Fields["Email"] != null)
                                    {
                                        sb.Append(" ");

                                        sb.Append(" ");

                                        sb.Append(" ");
                                       
                                        TemplateItem template = master.GetTemplate("{8FFC3E2B-C6F5-4A80-913D-E2A54D02FC20}");
                                        User currentUser;
                                        string domainUser = @"sitecore\UserA";
                                        currentUser = Sitecore.Security.Accounts.User.FromName(domainUser, false);

                                        Item oldVersionItem = master.GetItem(itemMainBio.Paths.FullPath + "/Versions");

                                        if (oldVersionItem != null)
                                        {

                                            oldVersionItem.Add(bioVersionName, template);
                                            using (new UserSwitcher(currentUser))
                                            {
                                                Item versionItem = master.GetItem(itemMainBio.Paths.FullPath + "/Versions/" + bioVersionName);
                                                if (versionItem != null)
                                                {
                                                  

                                                    versionItem.Editing.BeginEdit();
                                                    versionItem.Fields["VersionName"].Value = dr["Title"].ToString().Trim();
                                                    versionItem.Fields["MainBiographyNarrative"].Value = mainBiographyNarrative;
                                                    versionItem.Fields["ExperienceNarrative"].Value = experienceNarrative;
                                                    versionItem.Fields["__Workflow"].Value = "{E534CB0A-B877-49EA-BBB1-927EBD7853FE}";                                                   
                                                    versionItem.Fields["__Workflow state"].Value = "{E2CF5329-65A0-40EE-8971-88BDE0F68574}";                                                   
                                                    versionItem.Fields["__Default workflow"].Value = "{E534CB0A-B877-49EA-BBB1-927EBD7853FE}";                                                   
                                                    versionItem.Editing.AcceptChanges();
                                                    versionItem.Editing.EndEdit();
                                                }
                                            }
                                        }
                                    }
                                    else
                                    {
                                        sb.Append("
                                        sb.Append(" ");

                                        sb.Append(" ");
                                    }
                                }
                                catch (Exception ex)
                                {
                                    string msg = ex.Message;
                                }

                                sb.Append(" ");

                            }

                        }

                    }

                    sb.Append("

Sr. No.	Name	Email Id on File	Sitecore Email ID	Version Name	Match Found
" + counter + "	" + dr["lastName"].ToString().Trim() + " " + dr["FirstName"].ToString().Trim() + "	" + emailID + "	" + itemMainBio.Fields["Email"].ToString() + "	" + bioVersionName + "	" + "Yes" + "			" + "No" + "

");
                    divItemList.InnerHtml = sb.ToString();
                   
                }

            }
            catch (Exception ex)
            {
                string msg = ex.Message;
            }

        }

        private string formatHTML(string inputHTML)
        {
             try
            {
                var document = new HtmlDocument();
                document.LoadHtml(inputHTML);
                StringWriter writer = new StringWriter();

                XmlWriterSettings settings = new XmlWriterSettings();
                settings.OmitXmlDeclaration = true;
                settings.ConformanceLevel = ConformanceLevel.Fragment;
                settings.CloseOutput = false;

                var xmlWriter = XmlWriter.Create(writer, settings);
                document.OptionOutputAsXml = true;                   
                document.Save(xmlWriter);
                 var newHtml = writer.ToString();

                 return Convert.ToString(newHtml);
            }
             catch (Exception ex)
             {
                 string msg = ex.Message;
                 return msg;
                
             }

        }}