Edit GridView (ASP.NET 20 / C#)

I have a gridview with one column called "Advertiser". When the "Edit" button is clicked, the litteral-control shall be replaced with an textbox control, and the "Edit button shall be replaced with "Save" and "Cancel" buttons.

The datagrid is filled correctly with data, but I dont know how to write the "Update" or "Cancel" command.
Here is my code so far:


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ASPX
--------------

<asp:GridView runat="server" id="grdAdvertisers" AutoGenerateColumns="false" ShowHeader="false" OnRowEditing="grdAdvertisers_RowEditing">
    <EditRowStyle BackColor="yellow" />
    <Columns>
        <asp:TemplateField>
            <ItemTemplate>
                <asp:LinkButton CommandName="Edit" Text="Edit" Width="45px" runat="server" />
            </ItemTemplate>
            <EditItemTemplate>
                <asp:LinkButton CommandName="Update" Text="Update" Width="45px" runat="server" />
                <asp:LinkButton CommandName="Cancel" Text="Cancel" Width="45px" runat="server" />
            </EditItemTemplate>                  
        </asp:TemplateField>
        <asp:TemplateField>
             <ItemTemplate>
               <%# DataBinder.Eval(Container.DataItem,"AdvertiserName") %>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:TextBox runat="server" ID="txtAdvertiser" Text='<%# DataBinder.Eval(Container.DataItem,"AdvertiserName") %>' />
            </EditItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>


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ASPX.CS
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    private void bindAdvertisers()
    {
        SqlConnection Conn = new SqlConnection(Variables.ConnString);
        SqlCommand cmd = new SqlCommand("usp_AdvertiserNames", Conn);
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.Connection.Open();
        SqlDataReader dr = cmd.ExecuteReader();
        this.grdAdvertisers.DataSource = dr;
        this.grdAdvertisers.DataBind();
        cmd.Connection.Close();
        cmd.Dispose();
        Conn.Dispose();
    }


    protected void grdAdvertisers_RowEditing(object sender, GridViewEditEventArgs e)
    {
        //Response.Write(e.NewEditIndex);
    }