Step 1: Update iTunes to the latest version available and reboot your computer.
Step 2: Download BlackRa1n RC3 from our iPhone downloads page and install it, then reboot your computer.
Step 3: Plug your iPhone in your computer and launch BlackRa1n RC3. Click on "make it ra1n"
Step 4: Your iPhone will enter recovery mode. The regular recovery mode image on your iPhone will be replaced by a picture of GeoHot (same as image above).
Step 5: BlackRa1n will run on your iPhone and then it will reboot.
A pop up will show up asking you to donate. If you successfully jailbreak your iPhone, I suggest you send $5 or $10 to GeoHot.
Step 6: Once your iPhone reboots, you will have a new icon on your springboard. This is BlackRa1n. Now make sure you have internet connection and launch BlackRa1n on your iPhone.
Step 7: Choose what installer applications you want to install on your iPhone and then tap “Install”. I suggest only installing Cydia but you may install them all if you want to.
BlackRa1n will download and install the selected applications.
Step 8: Once done installing, your iPhone will respring and you should see your installer app on your springboard.
Step 9: Once your installer app (Cydia in our case) is installed. You can safely uninstall BlackRa1n by launching the app and selecting “uninstall balckra1n”.
Step 10: Reboot your iPhone. You’re done!
Step 11: install appsync from http://www.sinfuliphonerepo.com
Goto: Cydia > Manage > Sources > Edit > Add
Hopefully this jailbreak will go more smoothly than with BlackRa1n RC3. If you have any question or comment, please leave a comment below.