first you save it in C:\Program Files\Adobe\Photoshop CS\Presets\Brushes
then open up photoshop and on the right there should be a toolbar.

then theres an arrow on the right of Brush toolbar that looks a little like this > but shaded. you click on that and go to load brush and load your brush. then go through the brushes and on the bottom of it, there should be the brushes that you loaded.
