Copy the iCal URL from your schools calendar. Go into Settings > Mail, Contacts, Calendars, and choose Add Account, Other, Add Subscribed Calendar.
Paste the URL.
It probably looks something like this: "webcal://www.server.com/. . .ics".
Tap Next.
Change the description and/or add user login information if needed.
Save.
Go to your Calendar app and see if it worked. If it is a standard iCal server, it should.