J systems can be installed and distributed for free. To install see System/Installation.
The Studio page has basic examples of J, plus some of the online Labs. You might want to experiment with just a few of the most basic, useful elements of the language as shown in this minimal subset of J.
You need a helping hand! Fortunately, every experienced J user remembers what being a beginner was like, and many are ready to help with any question you may have. Subscribe to the J Forums and get your questions answered fast.
Documentation - Wiki
If you are a beginner, or if you just prefer your learning online, you should use NuVoc, The Wiki Dictionary of J. Start with the self-assessment. You can see the scope of NuVoc at its entry portal. Explore the primitives, or sample the tutorial pages listed at the bottom. A good start is the list of Absolutely Essential Terms which will explain the grammatical terminology used in J documentation.
J Graphic Analyzer
J, the language that lets you compress a screen of code into one line, has a tool that lets you see the execution of that line fullscreen. Use the Dissect addon while you are learning J. It's a good idea to assign a PFkey to dissect a line without having to retype it.
Documentation - Books
Reading the Primer is a good place to start. Even if you have considerable programming experience, there is much that is unique to J, and it is worthwhile to at least skim this book before jumping into the deep end.
- Learning J is an excellent introduction and overview of the core J language, see Learning J.
- J for C Programmers is a guide for making the transition from scalar languages to J. Early chapters describe J in terms of C, but the reader is weaned off C as the book progresses, and many J programmers ignorant of C have found the book a useful companion. Available in a J installation (via Help|Help), File:JforC20071003.pdf, or as a Microsoft Word 2003 file. You can also buy a hardcopy from Lulu. The book makes reference to a File:Jforc.ijs.
- Easy J is a gentle introduction for the complete beginner, see zipped pdf.
The J Reference Card is a very handy 2-page summary of J primitives available File:J602 RefCard color letter current.pdf.
See Showcase for more examples and articles on J.
The APL to J Phrase Book is a thesaurus which lists the common APL symbols and offers corresponding J primitives and sample expressions.
Check out NuVoc!!