Step 1) Read "The Art and Science of Digital Compositing" by Ron Brinkmann
Step 2) If you have access to a mac, buy "Apple Pro Training Series : Shake 4" by Marco Paolini, install the shake 4 demo and do all the tutorials. If you dont have access to a mac, your only option is to find a copy of shake 2.51 for windows. You can still do most of the tutorials in the Paolini book with this.
Step 3) Do all the tutorials which come with shake and read the documentation thouroughly. Look on the web for all the tutorials that you can find. This site has some, so does the CMI studios site. Read all the articles you can find about rotoscoping. Satisfy yourself that you have learnt to roto fast and well because this will probably be your entry point into the industry.
Step 4) Read "Digital Compositing for Film and Video" by Steve Wright
Step 5) Beg borrow or steal a 3 chip DV camera. Do whatever you have to do to shoot footage for your showreel. Comp it really well, as well as you can.
Step 6) Send the showreel to everyone you can find in the Yellow Pages (they have yellow pages in america?). Ask for an entry level position painting and rotoscoping. Be prepared to relocate.