Ajax-tabpanel-add events

How to add an event to the tabcontainer and click the BTN button to update the database? However, there is no event in the BTN. How can this problem be solved?
<PC3: tabpanel id = "tabpanel4" runat = "server" headertext = "add fault type">
<Contenttemplate>
<Div> <Table width = "100%"> <tr> <TD width = "100%">
<Asp: textbox id = "textbox_jieguo_add" runat = "server" width = "100%"> </ASP: textbox> </TD> </tr> </table> </div>
<Div> <Table> <tr> <TD>
<Asp: button id = "BTN" runat = "server" text = "add"/> </TD> </tr> </table> </div>
</Contenttemplate> </PC3: tabpanel>

</PC3: tabcontainer>

Thank you for your help.

The problem has been solved. You can also <asp: button id = "btn_addjieguo" runat = "server" text = "add" onclick = "btn_click"/>
Protected void btn_click (Object sender, eventargs E)
{

}