I wanted to demo the Http adapter in BizTalk 2006.
I found a useful article here http://dallas.sark.com/SarkBlog/jmsummers/archive/2006/02/13/2477.aspx.
But in the end I found the SDK example under C:\Program Files\Microsoft BizTalk Server 2006\SDK\Samples\AdaptersUsage\HTTPRequestResponse was simple and straightforward.
Online doco is here: