The application usage is pretty straight forward:
1. Create a pattern that only you will know about it
2. Select the apps you want to lock by pressing the lock icon
3. Exit the app and you're done.
Now anyone trying to open one of your protected apps a lock screen will show up and the pattern must be entered.
Every time you install a new app a pop screen will show up asking you if you want to block the newly installed application, which makes it very convenient so you don't need to open the app lock again in order to block it.
The Android robot is reproduced or modified from work created and shared by Google and used according to terms described in the Creative Commons 3.0 Attribution License.