how to change from email if to name?

protected void btnlogin_Click(object sender, EventArgs e)
   {

       LoginBLL objloginBLL = new LoginBLL();
       LoginModel obj = new LoginModel();
       obj.Email = Email.Text;
       obj.Password = Password.Text;
       obj.id = 0;

       obj.OrganisationID =Convert.ToInt32 (ddlorganisationname.SelectedValue);

       DataSet ds = new DataSet();
       ds = objloginBLL.logindetailsBLL(obj);


       if (ds.Tables[0].Rows.Count > 0)
       {
           if (ds.Tables[0].Rows[0]["role"].ToString() == ResourceManagementConstants.str_manager)
           {
               Response.Redirect("ManageUsers.aspx");
           }
           else
           {
               FormsAuthentication.RedirectFromLoginPage(Email.Text, false);
               Response.Redirect("FullProfile.aspx?id="+ds.Tables[0].Rows[0]["id"].ToString());

           }
           Session["OrganisationID"] = ddlorganisationname.SelectedValue;

       }
       else
       {
           ClientScript.RegisterStartupScript(Page.GetType(), "validation", "<script language='javascript'>alert('Invalid Username and Password')</script>");
       }
       Session["lgnFlag"] = 1;

   }