How to save database using EF

on Button click()
  AddEmailCampaign(ToAddresses, Subject, Content, FileUpload1.FileName,CreatedDates);

then,

 void AddEmailCampaign(List<string> ToAddresses, string Subject, string Content, string filename, DateTime CreatedDates)
        {
                   
            CRMEntities dc = new CRMEntities();

             tbl_EmailCampaign tbl = new tbl_EmailCampaign();

            //What is the LINQ way to join a string array

            tbl.Toaddress = String.Join(",", ToAddresses.ToArray()); // To Split The Array
            tbl.Subject = Subject;
            tbl.Contents = Content;
            tbl.Attachments = filename;
            tbl.CreatedDate = CreatedDates;
            dc.tbl_EmailCampaign.AddObject(tbl);
            dc.SaveChanges();
                     
        }