Japanese lessons?

Firstly I am wondering what dewanai means , and secondly, I wantto know if there are any good places to learn japanese on the internet or some places where I can buy books or cd's for learning the japanese language

Google "Learn Japanese." There are a lot of them.

Koichi's list:
http://www.tofugu.com/2008/10/21/top-10-online-resources-for-learning-japanese-for-free/

You should go to freejapaneselessons.com