3. With your iPhone connected run Blackra1n and click on the "make it rain button." (yes, it's that simple)
It will take a couple of minutes and your iPhone will reboot. You'll know that it's complete when you see this dialog:
4. Tap and run the freshly installed Blackra1n app.
You'll see a screen like the one above.
5. Here's the important part: Only install Cydia at this point. Resist the urge to install Rock and Icy – you can always install them later. I installed all three JB apps at once and Cydia gave a weird warning about not knowing its version number and Winterboard wouldn't run. If you install all three (like I did) your best bet is to restore and re-jailbreak.
Once you install Cydia, you're pretty much done. Take some time and try some software, especially Winterboard – which is found in Cydia under Featured Packages (scroll down). Oh, and don't forget to try some themes.