The internet! There are thousands of decent tutorials online.
If you don't like reading and learning from a screen (like me), you can always buy a book. Get a "JSP in 24hours" book, or something similar.
Have you got any programming experience? If so, you can skip the "...in 24hours" books, and step up to the more decent bibles.
JSP isn't very hard to learn, so you'll be able to write some basic stuff quite fast
Linear Mode
