Add events to custom web controls (front and backend code)

<script src="js/Jquery1." type="text/javascript"></script>
<script type="text/javascript">
function Register() {
if ($('#myRegister1_txtUserName').val() == '') {
$('#spanUserName').text('Please enter the username');
return false;
}
if ($('#myRegister1_txtPwd').val() == '') {
$('#spanPwd').text('Please enter password');
return false;
}
if ($('#myRegister1_txtPwd1').val() == '') {
$('#spanPwd1').text('Please enter password');
return false;
}
if ($('#myRegister1_txtPwd1').val() != $('#myRegister1_txtPwd').val()) {
$('#spanPwd1').text('The password must be the same for the two times');
return false;
}
if ($('#myRegister1_txtEmail').val() == '') {
$('#spanEmail').text('Please enter the email');
return false;
}
return true;
}
</script>
<table>
<tr>
<td>Username:</td>
<td>
<asp:TextBox ID="txtUserName" runat="server"></asp:TextBox></td>
<td><span ></span></td>
</tr>
<tr>
<td>Password:</td>
<td>
<asp:TextBox ID="txtPwd" runat="server"></asp:TextBox></td>
<td><span ></span></td>
</tr>
<tr>
<td>Confirm password:</td>
<td>
<asp:TextBox ID="txtPwd1" runat="server"></asp:TextBox></td>
<td><span ></span></td>
</tr>
<tr>
<td>Email:</td>
<td>
<asp:TextBox ID="txtEmail" runat="server"></asp:TextBox></td>
<td><span ></span></td>
</tr>
<tr>
<td></td>
<td>
<asp:Button ID="btnRegister" runat="server" Text="register"
onclick="btnRegister_Click" OnClientClick="return Register()" /></td>
<td>
<asp:Label ID="Label1" runat="server" Text=""></asp:Label>
</td>
</tr>
</table>