It's kind of a wide open question with a lot of answers. The ARSystem is really a toolkit that allows you to build applications without really knowing any specific programming language. It does sometimes help if you are able to do programming in one of several languages: Java, Perl, C, Visual Basic, HTML, Javascript, VBScript, JSP, etc... There are several API's that you can use, JAVA, C, Perl, and a couple of 'wrappers' like James Croom's ARS42i component that let you do program in Visual Basic, Javascript, VBScript, etc... to name a few.
To be honest, the quickest way to learn the system and what you can do in it is to go to the Admin classes (at least the first one or two), and then play around in it. Build an actualy application, even if it's something like a 'What Restaurant should we go to?' system...
Actaul documentation is available from
Remedy Support if you have a valid support contract. Otherwise, if you had a physical shipment of the software, the documentation should have been included with it. Or your sales rep. should be able to obtain it for you, as well.
Does that help?