Put a link button in grid view and give its
commandname="ChangeColor" commandgrgumen=<%EVal("sno") text="Change"
Sno is serial number of the table starts from zero
int index= int.Parse(e.CommandArgument.ToString());
in gridviewcommand event write below
if(e.commandName=="CahngeColor")
{
griview1.rows[index].backcolor= System.Drawing.Color.Red;
}