Carbon Filters

I'm looking to set up carbon filters because I don't want smell getting out. I'm planning on growing somewhere between 2-4 plants in a 5' x 9' closet. What exactly is a carbon filter and how do you set it up? If anyone could link me to something or give me a briefing, it seems to be the only thing im not sure about in the growing proccess.

A carbon filter filters the air as it passes through the activated carbon, taking away the odour particles, And you can set it up by putting a fan on the filter sucking air through it and the other end exhaust out of the grow room

Watch 2:00 into this video. Good luck.

[youtube]LYVHDlWFmj0[/youtube]

What if I'm planning on starting a small op in my closet (5' x 9'). How would I get the odor out of the closet basically?