Well, if you look at the top of the ethical hacking thread list there are some nice links to sites that will come in handy so first step is to get your tools and utils ready, then you must learn how to use them, most of them are very easy to use but some may be tricky in the beginning. The best tool to start with is cain and abel from http://www.oxid.it
and then start by hacking the computers on your local network before you go to the internet just to give you more of a feel of what hacking is all about and then also what cracking is all about. Get some nice tutorials and install linux on one partition of your Hard Drive, kubuntu 7 gutsy is a very nice one to start with. Learn basic programming skills to find out which one you prefer and then go deepr into that language to master it, C++ is the best but the most difficult for some. VB.net is easy but limited. Knock yourself out!