Header Vaiables

Hi everyone, im new to this forum and especially new to visual basic but this looks like a really great place to start!

Im trying to modify some visual basic code behind for an asp website that my company uses. At present the code behind takes username and password from a form on the asp page and runs when a user clicks enter on the asp page.

Im trying to get it so that the code behind takes a header variable from anopther application called siteminder so that users no longer have to enter their username into the page/app. I cant find any info on vb recieving header variables anywhere, would also like to know how to get the code behind to run without a click?

Sorry, im a real novice with all of this and its just fallen into my hands, if anyone has any devent resources i could start at that would be great.

Cheers

Rhys