I really like Core Servlets and JavaServer Pages. Have a look at the web site for the book here:
http://www.coreservlets.com. You can even download all the chapters individually at PDFs for free from
http://pdf.coreservlets.com. The book's web site includes links to tutorials, etc. It's a great way to get started.
Now, if that's not enough, the book has a follow-up called More Servlets and JavaServer pages. Like the above book, it has a web site:
http://www.moreservlets.com as well as downloadable chapters here:
http://pdf.moreservlets.com
Note that you're going to want to learn JSTL (
Java Standard Tag Library) as well. I used the book JSTL in Action from Manning Publications, which I liked very much.
Plus, there's lots of great help on these forums!
Good luck.