1) I just added the pic to a new document. Choose a color for the background.
2) A selection needs to be made. Hold Ctrl and click on the layer preview in the layers palette.
3) Layer > New Fill Layer > Solid Color. Choose the color you wish, I went with black. You'll notice there is a layer mask on the color fill layer.
Should be like this so far.
4) Choose the brush tool and make sure the foreground is set to black because that is used to erase from the layer mask.
5) Take the black brush and go over the layer mask to make what you want to keep from the original pic visible. Be sure to change brush types and sizes for certain things.
6) You are basically done. What you do next is up to you.
And this is my first time doing this, so it can't be that hard.