NOTE: This only applies to Android devices and Windows laptops. If you have an iPad or Apple laptop the printers should just magically appear.
Log into your school google account (firstname.lastname@example.org) then go to Google Cloud Print. If you don't see the Lincoln Lutheran printers then you are logged in with a different Google account. You can switch accounts from the icon in the upper right corner of your browser window.
To print from that browser screen use the [Print] button on the left.
To setup your Android Device so that you can print without going to that website you follow these steps to turn Cloud Printing on:
Connections -> More Networks -> Printing -> Cloud Print (turn on)
I really do't know much more about it than that. There also seem to be some apps for Android that are suppose to make this easier.
To print from your Chromebook just choose print and it should work.
To print from your Window's Laptop, use the Chrome Browser and Google says that it should just work.
Finally, here's an article that you might find useful. It describes what you can do with Google Cloud Print and how to do it from a variety of devices.