Some people have asked questions about how to do things with the editor used in the "Mailings" section as well as others.
CivicCRM and PowerBase uses a publicly available editor for this purpose. It's called CKEditor and here's a link to the instruction manual:
http://docs.cksource.com/CKEditor_3.x/Users_Guide
Category:
Managing Contributions
Email and Postal Mailings
Event Management
PowerBase - General