Anyone able to tell me how to do a compression test?

I am borrowing a tester from a friend, and wondering how to do it.

Please be very basic, as i've never done it before.

Also please let me know what kind of PSI i should be seeing.

I will be using a regular piston compression checker.

 

All the way to the bottom of the 2nd gen page on the far right is a text box. Type in compression test and click the go button.