Your question is kind of like "please tell me how to learn everything about mathematics". There are many, many different aspects of both. You need to focus on a few areas, or at least start with a broad overview of the entire platform. First I would review these articles/documents:
http://www.symantec.com/docs/HOWTO32608 (reference to all Altiris 7 Best Practices articles)
http://www.symantec.com/docs/HOWTO30370
http://www.symantec.com/docs/HOWTO9811 (Altiris 7 Planning and Implementation Guide)
What is your main goal of evaluating Altiris? Do you want to deploy patches, manage/track hardware and software assets, gather inventory, perform remote control, deploy PCs/servers, etc?