If you're using maya at home and you're computer is not a netwroked computer, maya help might not work. So what you should do is one of the followings:
1- Easiest way is to just copy one of the addresses below and paste it into your browser(You have to have maya installed!):
Maya 8.0 Help:
file:///C:/Program%20Files/Alias/Maya8.0/docs/Maya8.0/en_US/wwhelp/wwhimpl/js/html/wwhelp.htm
Maya 8.0 Mel Commands:
file:///C:/Program%20Files/Alias/Maya8.0/docs/Maya8.0/en_US/Commands/index.html
Maya 7.0 Help:
file:///C:/Program%20Files/Alias/Maya7.0/docs/Documents/Maya7.0/en_US/index.html
2- Make your computer a server (I will make a tutorial seperately).
3- Open the port that you see in your web browser (A port is a number after ":" in the address bar).