How to build a go kart?

My friend and I are interested in building a go kart with a top speed of between 30 and 40 mph. However, we know next to nothing about how to build one. Does anyone know any websites that put it in plain English? Where would be a good place to buy an engine? If we buy a complete chassis kit (http://www.google.com/products/catalog?hl=en&q=go+kart&bav=on.2,or.r_gc.r_pw.&biw=1127&bih=694&um=1&ie=UTF-8&tbm=shop&cid=14532977528361303040&sa=X&ei=mZMOToyUF8Hk0QGkmKmjDg&ved=0CFMQ8wIwAQ) what else would we need to put it together? Any information will help. Thanks!