When you visit the library without a class, you are expected to sign in. You are also expected to sign out if you leave before the end of the period.
The sign-in desk is straight ahead of you when you enter the library. On one of the two laptops, enter your student ID number (AKA your lunch code) into the field pictured on the left here, and click Submit. If you leave before the end of the period, click Out to the right of your name. That's all!
For a demonstration, watch the video on the right.