Dragging the checkbox into the template field will add the checkbox to every row in the GridView.
The following is a Gridview with one column, which uses a template field and has only a checkbox in it bound to my data source:
Code:
<asp:GridView ID="GridView1" runat="server"
AutoGenerateColumns="false"
DataSourceID="SqlDataSource3"
EnableViewState="false">
<Columns>
<asp:TemplateField HeaderText="ND">
<ItemTemplate>
<asp:CheckBox ID="chkBxNoData" runat="server"
Checked='<%# Eval("noData") %>' />
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>