How do i wire up a computer fan for my cabinet?

Hi guys im new to growing and need some help on setting my cabinet up. i plan on using a ready made old cupboard type thing or like a filing cabinet, however i get the basic principle of intake at the bottom and exhaust at the top but how do i wire up the fan from a computer as it has little gay plugs and clips on it etc. whats the easiest way just to make it work and also what do i do about excess water that runs out of the plants?
oh and another thing the cabinet should be completely light proof right but how do i make the exhaust and air intake light proof?

Thanks guys all replys and tips would be muchly appreciated :)