Help Urgent!!!!!!!

 Hello Friends,
How to perform two actions when button(submit) is clicked.
OnClick="btn_Click" onMouseDown="return CheckLength();" i think its wrong..please tell how to perform two tasks when single event raised ie when button click....
I tried Below Program
<%@ Page Language="C#"  %>
<html>
<head>
<script language="javascript">
     
            function Check()
{
   
            {
                if(!document.form1.agree.checked){alert("Please Read the guidelines and check the box below");
            & ...