Retrieve value of the row when clicked in ASP.Net

HI sir

 Sorry I did not know about Add code part. I will make it sure that I would do it from now on.

 I am using Comman field button in each row of a gridview. I am displaying  trainerID,      names,mobile numbers .  The name of my command field button is View Profile. 

 I want to retrieve the trainer iD  when i Click on the command field b

I always get row.Cells[1].Text as null.

Please  help  me out.

Thanks..

 protected void GridView1_SelectedIndexChanging(object sender,GridViewSelectEventArgs e)
        {

                   GridViewRow row = (GridViewRow)GridView1.Rows[e.NewSelectedIndex];
                   Session["contactID"] = row.Cells[1].Text;
                   Response.RedirectPermanent("~/TrainersDetails.aspx", false);
   
        }