Like I said...there is a SG2 subforum, look in the 'All things root' section for the info you need. The SG2 is pretty fast, not sure there's really much to gain by overclocking.
Maybe I should add this...
Ask yourself what you need to do that actually requires root or if you just want to play with the phone. For most users it's probably the latter.
Android and hardware have come a long way. Storage space is usually adequate and a lot of customization is possible without root. For regular users there's just not as many things that require root as before. I haven't bothered to root my daily driver in a long time and nowadays usually recommend against it.
No offense to hard-working developers, but custom ROMs do vary some in terms of quality, stability, functionality and features. Rooting will void your warranty.
If you decide you really do need/want to root, look in the 'All Things Root' section of your phone's subforum. Plenty of info is available. Also, Google search is your friend. Do a LOT of reading. It's possible a mistake could 'brick' your phone (make it unusable). Make sure you understand why you're doing it, the exact steps required and all the terminology, and have a recovery plan and backups in case things go bad. Nobody likes to bail out a n00b just because he simply failed to do his homework first.
