Detailed information about pattern, syllabus and strategy for GRE exam. How many months of preparation is necessary to crack GRE exam?

Hi.. iam a 2013 passed out.
Iam very much intrested right now to crack GRE. i feel i have worth and my hardwork will reach me there.
but i have problem that, iam un aware of GRE patterns, syllabus and way to achieve iam new to all these so plz help. how many months of preparation is needed to crack it.