How do I install a case fan to the bottom front of my case. p.s i'm a newbie so be easy

Depends on the case, some have plastic fan clips and some you have to get fan screws.

where do I plug it in, theres multi coloured wires with a white connector thats not plugged in

Try to find a wire(red/black) with molex connector from the PSU itself if the fan is a big one...if its a fairly small one(w/ red, yellow, balck wires) , the connectors should be a female 3 pin, try searching jumpers/pins on your mobo with the help of your manual.