In most iOS apps there is a Action/Share button that looks like this:
Press the Action/Share button to get a list of options on what to do with the the current content your viewing.
Scroll down the list and you will see that Print is usually be an option.
After pressing Print, you will see a new window showing Print Options. Here you can select the printer, select how many copies you want to print, select a specific page range to print, select Double or Single sided pages, etc.
Press Select Printer and choose a printer. Some printers you will see have a lock icon, you must enter credentials for the first time to print to these printers.
For Staff your Username is your Lastname.Firstname
For Staff the password is same as your email Password
For Students their Username and Password is the same one printed on the back of their iPads.
Some Printers will be name with "Follow Me". These printers hold off on printing your job until you physically go to the printer and scan your School ID Badge to release the print job. The FollowMe printers are a great option for printing large jobs, or if what your printing contains sensitive information.
Once you have entered your credentials to the printer, and you have set all your Print Options the way you want for this Print Job, press Print in the top right corner of the window.