No problem. I've explained it before a few times, but I don't mind doing it again.
What I do is get several differnent colors for a dry brush. Depending on the color of the figure parts that are to be dry brushed, I try and find an opposite color. Like if it's a black figure, then maybe I will use a yellow or white color for the dry brush. If it's a light colored figure, then the dry brush will need to be applied with a darker color.
Technique - On a paper plate (or whatever) put a couple of smears of paint onto it. Use your paint brush (not a fine detailing brush, but a thicker one) and dab it in the paint some. Then run the brush onto a surface to get rid of "most" of the paint. You can then start stroking the brush bristles against the figure, and ever so slightly the paint will appear to start showing over the details of the figure's sculpt. The idea is to have to "force" the brush firmly against the figure to get any paint off the bristles. Repeat as necessary.
Dry brushing seems to work best on a figure that has already been painted. For example, if you were to dry brush a TIE fighter pilot, I would suggest repainting him black first, then doing the dry brush.
