Jailbreak your iPhone, iPad, or iPod touch

1. First download Greenpois0n Absinthe 2.0 2.0.1 to your computer from our downloads section. It is available for Mac, PC, and Linux.
2. Next, install the program and open Absinthe with your iPhone, iPad, or iPod touch plugged into your computer.

3. Click the Jailbreak button to begin the process.

4. This process may take a while to complete so you'll have to be a little patient. Mine took about 6 minutes total. Your device may say Restore in Progress, that's okay.
5. When you see the message Done, enjoy! on your computer you can go ahead and unplug your iPhone, iPad, or iPod touch.
6. You're done! Cydia will be on your Home screen and you're good to go!

Source : Imore