onClick question

Hello
I have a TextBox for a user to type in his email address when he forgets his password. The idea is that he clicks the 'Send' button, that button is then disabled so that he can't click on 'Send' again, and a message should appear informing him that 'a password reset has been sent' to him. That message should only appear when he clicks on 'Send', but I can't quite get the code correct.
The aspx file looks like this:
<asp:TextBox runat="server" ID="UserEmail" /> <asp:Label ID="MailSent" runat="server" Visible="false" Text="A password reset link has been sent to you" /> <asp:Button ID="btnPassSend" runat="server" OnClick="btnPassSend_Click" Text="Send" /> And my aspx.vb file:
Protected Sub btnPassSend_Click(sender As Object, e As EventA ...