The ATLAS Workbooks
These are intended to get you started with the general ATLAS computing environment. They focus on issues you are liable to encounter, but don't discuss things specific to any particular analysis.
Using the Grid
Version Control
Version control systems allow you to store past versions of files and quickly see your revisions. You can also easily share your projects with others. The use of Subversion (SVN) is mandatory for ATLAS software management. For local projects where SVN may be too heavy, you may also try Git; they have the same basic principles but differ in specifics. There is also a bridge between Git and SVN.