You can trade btc you mine for gigahash, meaning: Mine as usual with your miner/gpu/usb/asic - Either withdraw them OR sell them for gigahash!
You sell your bitcoin(however small it may be) for hashrates!
So, yeah that's pretty much it. You can read up on it on the site.
But if you do register, please, please, do it under my name. :D <3
https://cex.io/r/1/Noxx/0/ <- My referal link, would appreciate it if you registered under my name. That way its a win-win.

Thanks mates!