This is one of the funnest parts about Jailbreaking your device. Youll love this!
Okay so lets get started!

Step 1: Open Cydia, hit "Sources". (Skip to Step 5 if you already have ModMyi.)
Step 2: "Edit" then "Add ".
Step 3: Type this in exact;y!
http://apt.modmyi.com
Step 4: "Add" and install.

Step 5: Open Cydia, hit "Search". And search for "Zeppelin".
Step 6: Hit "Install". And wait for it to finish.

Step 7: Respring or reboot.
Step 9: Go to Settings. And scroll down until you see Zeppelin.
Step 10: Hit "Theme" and go ahead and choose whichever youd like.
And thats it! You can go to Cydia and search for Zeppelin and look at all the ones you can install! Theres hundreds!
If youd like to learn how to make your own out of an image click here :)