Step 1: Install 5.0.1 Final.
Step 2: Open RedSn0w 0.9.9b8 and select Extras > Specify Firmware > then point it to the iOS 5.0 firmware IPSW.
Step 3: Go back to the main screen of RedSn0w and place your device into DFU mode. Click Jailbreak, and then select Install Cydia.
Step 4: Your device should then jailbreak, but note that your Cydia icon will be white because it is a tethered jailbreak. To boot tethered you will need to place your device into DFU mode again.
Step 5: From the main RedSn0w page, select Extras > Specify Firmware > and point it to the iOS 5.0 IPSW.
Step 6: Choose “Just Boot” from RedSn0w’s Extras menu, and it will perform a tethered boot.
iOS 5.0.1 Final should now be fully jailbroken. If you’re in need of a more in-depth RedSn0w guide, venture over to our RedSn0w page.