How to rig my Nikon D3100 to take a picture every 15 seconds?

So I can make a time lapse of clouds going by.
I'm not sure if the camera even does that at all. I'm new to this stuff. :\ If any of you could give me some help I will greatly appreciate it.

Nikon makes an application called camera control that will make time lapse images. As does a website calle DIYPhotoBits. I have used the latter to shoot a time lapse series of a burning candle which I later assembled into a movie using Windows Movie Maker.