You can add shortcuts in iOS 7 by launching the Settings App and navigating to: General > Keyboard

Here, you'll see the below screen at the bottom of this screen is a Shortcuts section, which includes a button named Add New Shortcuts.

Add New Shortcut is right at the bottom of this screen.

Adding new shortcuts is simple and easy. All you need to do is choose the phrase you want to create a shortcut for, and decide on a suitable shortcut. For example, you could configure iha to add in I hate acronyms and wtf to add what the f**k