how to display the dropdownlist data into gridview by clicking the command button save?

DataTable dt_ddl = new DataTable();
          dt_ddl.Columns.Add("TextFeild");
          dt_ddl.Columns.Add("ValueFeild");
          for(int i=0;i<ddl.items.count;i++)>
          {
            DataRow dr = dt.NewRow();
            dr[0] = ddl.Items[i].Text;
            dr[1] = ddl.Items[i].Value;
            dt_ddl.Rows.Add(dr);
          }
          GridView1.DataSource=dt_ddl;
          GridView1.DataBind();