I get lots of mail from people asking how can they learn hacking and where can they test it and so on. my answer to them is that "you have the whole web to learn and test your hacking skills" , provided you dont break the limits. Hacking should always be to get good out of it . I love the recent Crome advertisement on TV which says "the web is what you make out of it" . This a completely true statement .
Few days back I came across a very intresting application designed in JSP and Servlets that contains lots of practice lessons for hacking . The lessons cover all the basic and advanced techniques with hints and solutions and gives you a very good understanding of real time hacking . I feel that all the biggeners and even the experts hackers should defiantly give it a try as there are lots of things to twist every level of hacker.
I myself enjoyed the lessons alot and really enjoyed hacking them . And the best part is that you also have a scorecard to monitor your performance. The project is developed by OWASP and can be found at this link - OWASP-WebGoat .
You will also need an additional tool called webScarab whose link is provided in the webgoat application itself and you can find a complete tutorial on webscarab here - Intercepting WebScarab request/response using Webscarab to hack web applications.
The installation and usage is simple and you can find complete documentation at the above mentioned link .
All enthusiastic hackers should try out the lessons as it will give you lot of practical exposure.
In case you face any technical difficulty ib lessons or installation then feel free to add your problems here in the comment section and I will try to help you out .
Do give a try , you will surely love it .