Crud action with entity framework on single view in a tab?

Hi,
i'm beginner in asp.net mvc,i'm using tab for action of crud 
tab1 - show user list,
tab2-add user
tab3-edit user on dropdownlist selection ,get all details in textbox on dropdownlist selection.
 

tab1 - show user list,
tab2-add user
tab3-edit user on dropdownlist selection ,get all details in textbox on dropdownlist selection.
 

the question how can i perform it .i'm completed tab1 and tab 2 task ,but unable do tab3 work which is how get selected detail set in text box from database on selection on dropdownlist (in dropdownlist show the list of employee name)

please help 
Thanks in advance

public ActionResult Qsupport()
      {
          UserViewModel userViewModel = new UserViewModel();
          using (CompanyDBEntities e = new CompanyDBEntities())
          {
              var userLists = e.sd_admin.ToList();
              var username = new SelectList(e.sd_admin.ToList(), "uid", "uname");
              ViewData["username"] = username;
              userViewModel.adminsList = userLists;
              userViewModel.admin = new sd_admin();
              return View(userViewModel);
          }
      }


      public ActionResult AlluserList()
      {
          return PartialView("AlluserList");
      }
      public ActionResult AddUser()
      {
          return View();
      }
      public ActionResult AddUser(UserViewModel userViewModel)
      {
          if (ModelState.IsValid)
          {
              sd_admin sd_Admin = new sd_admin();
              DbObjectConverter.CopyProperties(userViewModel.admin, sd_Admin);
              //sd_Admin.password = user.User.Password;
              sd_Admin.rights = "";
              sd_Admin.ustatus = "";
              sd_Admin.lastupdated = DateTime.Now.ToShortDateString();

              using (CompanyDBEntities e = new CompanyDBEntities())
              {
                  e.sd_admin.Add(sd_Admin);
                  try
                  {
                      e.SaveChanges();
                      string uid = userViewModel.admin.uid;

                  }
                  catch (Exception ex)
                  {

                  }

              }

          }
          return View("Qsupport", userViewModel);
      }