mod_rewrite/.htaccess

[Prosis]

Ok, I've read a bunch of topics concerning this and I don't understand anything lol I suck but this is the first time I set something like this so I apologize for this question.

I have two domains one .ca and one .com.  Right now, I have the .ca added in my domain list so that, with nameservers, it points to the root on my freepgs server.  Now I want the .ca to point to one folder that contains the website for the .ca and the .com to go to another directory with the website for the .com.

How am I to do that?  What is mod-rewrite? How do I set this up?

I really sorry, I know this question has been answered but I need a clearer answer because I don't understand anything.  I am a real newbie concerning the matter.

Thank You

[Prosis]

Also, after using mod_rewrite should I make my domain point to the subfolder or root?

And I'm asking because I tried what was written in this topic: http://forum.freepgs.com/?topic=584.msg2327#msg2327 and it failed.. because I have no idea what I'm doing basically

[Prosis]

11 reads, no one can help me? Please?