While Fair Use guidelines do allow for some reuse of copyright-protected materials within an academic/classroom context, if you plan on using the work of others in a public performance or publication (including on the web), you will need to seek out the permission of copyright holders or make sure to use images that are either in the Public Domain or that use Creative Commons licensing. See LITS' Copyright Research Guide for more information about Copyright, Fair Use, the Public Domain, and Creative Commons.
Photoshop comes with many fonts already installed for your use. It is possible to install additional fonts, but only on your personal computer. All campus public and lab computers are frozen (meaning users can't make changes to the software installed) in order to ensure that they run consistently all year. If you have Photoshop on your personal computer and want to install additional fonts, you may find these tools useful: