Caption's for checkboxes

asp.net/c#
One of my grid view's is 5 columns, two of the columns are checkboxes (row 2 and 3). One is labeled x, the other is labeled y. I was wondering what the caption should read to display which check box is displayed. Below is a caption I have to display the int that is different in every row for the 2nd column which works. But I;m not sure how to do it for checkboxes.

gvtask.Caption = gvTask.SlectRow.Cells[1].Text;