You can get info on the test on www.gre.org, and you can register on the gre.org site.
Basically you should study for about 2-3 months depending on how much vocab you need to study. You prob don’t need much math prep, so focus on verbal.
You MUST get the official practice questions book (info on gre.org) and the official tests, too (called Powerprep, free on same site). I also used Cracking the GRE from Princeton Review and would definitely recommend it. Best review guide and the tests are very good. And study your vocab!! I did not get a big words list (but I am American, so…) but I have Word Smart for the GRE and that has a great list.