when I checked checkbox, delete checked_row on gridview

Question

hi.
I asked one week ago: "update all record"
now, I want to delete one record on gridview when I checked checkbox.
there is a checkbox on gridviewrows.
for example; if I checked checkbox on second row. The second row will deleted.

if I Checked checkbox. that code will run.
protected void checkbox1_checkedchange.............
{
     DELETE FROM table1 WHERE  messageId = .........???(which row/message checked .)
}

I can't fix that Which row checked.

how can I that.

Note. I am sorry (very very sory for my english)