Back to Basics Help Needed

About 2 years ago I cobbled together a very simple website that has been working fine. Now I want to improve the website. I discovered that I am back to the beginning in my understanding of ATAHUALPA.

1. I looked for ATAHUALPA documentation by the developer and cannot find it. Where is it?
2. I believe there used to be a posting by the developer on the compatability of the ATAHUALPA releases with the latest releases of WORDPRESS. Where is that statement?

Once I get familiar with ATAHUALPA again, the first thing I want to do is to make the header fixed or sticky. Can that be done within ATAHUALPA?

Any help would be most appreciated. Thank you.