Try This :
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
int x = System.Convert.ToInt32(e.Row.RowIndex);
CheckBox chk = (CheckBox)e.Row.FindControl("CheckBox1");
}
}
hope you understand and this will help you...
in Item Template :
<asp:TemplateField HeaderText="Select Document">
<ItemTemplate>
<asp:checkbox id="CheckBox1" runat="server" />
</ItemTemplate>