but i dont know how to carpet it

 

carpeting is very easy. there is a tutorial on sounddomain but the site is down right now as usual... or you could paint the box. just sand it nice maby a bit of wood filler to fill the screw holes. save your self alot of money and you lean how to build a box its win win.

 

where would i buy the plastic piece for the port?

 

pvc or abs pipe. check out your nearest hardware store ( home depot/rona etc)