Grenade help

I'm trying to get this grenade script to work, but I can't for some reason.
How can I get it so whenever I click the right mouse button the player throws a grenade?

Heres the link to the grenade script:
http://www.garagegames.com/index.php?sec=mg&mod=resource&page=view&qid=7075

Thanks for the help,
Nathan