Email Form on Content Page

Ok I am totally new at this whole ASP and VB thing...but I learn by doing so here goes....
I have been trying to use the sample code to create an email feedback page as provided by:
http://www.4guysfromrolla.com/webtech/080801-1.shtml
If I create a BLANK PAGE it works great...
However, I clearly want to keep the site's feel and therefore am using a Site.Master page...
Now it fails when it gets to:
Sub btnSendFeedback_Click(sender as Object, e as EventArgs)
The error that I get is: Parser Error Message: Only Content controls are allowed directly in a content page that contains Content controls.

So where do I store the subroutine that gets called on a button click?
Thanks. -Mark ...