Its really easy though, what you need to get first is
1) Combolists this can be emailass or userass depends on the site you testing
2) Proxy which you can google for free proxy or if you want cheap and reliable proxy find a good paid proxy provider such as stormproxy.
3) Tools suchs Sentry, Snipr, Storm, BlackBullet. Although only Sentry & Storm is a free tool
4) Configuration of the site you want to test