I want to start jailbreaking.
Can you downgrade to 6.0.2 in order to be able to jailbreak?It depends on what you wish to know. If you want to know everything, then read around the forum and/or search on the web. You aren't going to get information just fed to you though as there's so much out there
If you want to jailbreak iOS 6, then you have to be on 6.0-6.1.2. You would use evasi0n. 6.1.3 and 6.1.4 is unjailbreakable at the moment. The only exception is the 3GS or 4 but would net you only a tethered jailbreak
http://idownloadblog.com is a pretty reliable and good source of information for jailbreak related stuff
Can you downgrade to 6.0.2 in order to be able to jailbreak?
The most trustable things:
Redns0w for tethered jailbreaks on iOS 6(or untethered on iOS 5),downgrades to IOS 5 or below and some other handy stuff.This includes baseband managing;
Evasi0n for iOS 6.0 through 6.1.2 untethred jailbreak;
sn0wbreeze for untethered jailbreaks on untethered jailbreak suported firmwares,including the old bootrom 3GS downgrade,also for SHSH blobs managing and creating custom firmware for downgrade.This includes baseband managing;
I'm not too sure why but for some reason, I prefer iFaith over sn0wbreeze
iFaith cant jailbreak-it just Dumps,verifys and saves SHSH
Besides,iFaith is built into sn0wbreeze
wrong (again)
iFaith also makes custom signed IPSW which you can restore to.