How to get started?

First of all - one of the main interfaces to an IBM i for programmers still is the "green screen", aka a so called 5250 telnet terminal emulation. Ask your seach engine for "TN5250" for free or commercial products, or give the following products a try: You can also try IBM i Access Client Solutions if you have access to IBM ESS software at:
IBM web site (sorry we may not publish a direct download link)
Advanced programmers may use the free eclipse based package to be found here, but for all features you might heed the IBM Rational developer for i which is some costy but offers a lot of modern features for programmers.

You might want to use pure eclipse with these (or other) plugins:
Sourceforge - iserieslegacy

We also highly recommend MIWorkplace by Mihael Schmidt

After you got your 5250 emulator package, please proceed to SIGNUP here for your free IBM i account and start within some minutes!