Fastest way!!! go to www.jailbreakme.com/ on your device, and install the app! takes 5 seconds!
tutorial: www.redmondpie.com/jailbreak-4.3.3-untethered-iphone-4-3gs-ipad-ipod-touch-using-redsn0w-tutorial/
download latest redsn0w: blog.iphone-dev.org/post/5239805497/tic-tac-toe
Redsn0w 0.9.6 rc18
Once you have Cydia, you can add source: Hackulo.us, then install Installous 4.
www.limera1n.cc/2011/10/download-ios-5-ipsw-firmware-iphone-4.html