There are several ways to find documentation. Where to look will depend on exactly what kind of help you are looking for:

Introduction If you are looking for a "high-level" overview of how ASE works and what it can do, you should read the introduction.
ASE Manual Browsing the manual will also give you an overview of how ASE works and what it can do.
Tutorials If you are not sure what you are looking for, try working your way through one of the tutorials.
Examples If you are looking for information on how to do something, look for an example in the collection of example scripts.
API Application Programming Interface: If you are an experienced ASE user, and you know exactly what you are looking for, then the computer generated documentation may be the place to look. We are currently using epydoc for automatically generating documentation from docstrings in the code.
Mailing list If you don't find what you are looking for, you can always ask a question on the ASE mailing list or search the archives.
Source code If you are a user at grandmaster or wizard level, you may want to look at the source code directly. It should be installed in something like /usr/lib/python2.2/site-packages/ASE. You can also browse it online.
Bugs What to do if you find a bug? Which bugs are already known?
Development Documentation for the developers.