You can start reading about the Oracle Applications on the Oracle site: http://www.oracle.com/applications.
Read about the Oracle Applications functions and methods for patching the applications. Check out the Oracle Applications specific information at: http://www.oracle.com/appsnet/content.html
Another great source for information and contacts is OAUG (Oracle Applications Users Group) which is independent from Oracle, and is an association of people who use the applications. That site is: http://www.oaug.org/
Use your network: I'd make friends with your accounting department. They may be using Oracle Applications, or know someone who does. Understand that people tend to be polarized about Oracle Applications, depending upon their installation experiences. You may get some very strong opinions.
If you take a course, you may want to consider the Oracle Applications Systems Administrator class.
This was first published in October 2003