To get results like mine you need to do a lot of things because this isn't simple. Within time you will understand how to do this... because each step isn't complicated.
But how to use the brushes I can tell you. Once you downloaded it, get into your photoshop and with the brush tool right click on the canvas. This brings up a menu. Click Load\Replace Brushes and then 'open' the file you downloaded. Now you can use it. Hope I helped