For that use join while getting data, and after that you can assign result to GridView.
like this-
SqlConnection con = new SqlConnection("con string ");
SqlDataAdapter da;
string mySQL = "Your join Query";
da = new SqlDataAdapter(mySQL, con);
DataSet ds = new DataSet();
da.Fill(ds);
GridView1.DataSource=ds;
GridView1.DataBind();
Try this and let me know;.