how to put signup form in every post?

https://www.realestatetripleplay.com

I thought it was simple, but after spending the past 45 minutes trying to get it to work, thought I would post here instead.

I just want a simple form that shows up on each and every post I write automatically, to encourage people to join the mailing list. The information I want is on the left hand side at top of my main page and just asks for name and email address. I tried modifying the main page.php file in wordpress, but no luck, nothing changes.

I am sure this is easy, but I am missing how to do this.

Thanks!