Create as in, write your own, or install one of the many free ones?
If you want to write on you'll need a vast understanding on PHP at the very least. If you want to install one, that's pretty easy and you'll just need to grab a free one. PHPBB, PunBB, and SMF are good ones.
Installing them varies amongst what you pick, but the principle is the same: upload files to web server, make MySQL database, run the install script.
As far as profit, yes you can make profit with ad scripts, such as Google AdSense. The amount of traffic you'd need to make money simply from page hits is quite a bit, I'd say a couple thousand unique visitors a month. However if say 100 people a month click an ad, you'd get a bit of money that way because ads can go for up to $10 per click, depending what the ad is about.