1. Go into your C-drive and create a directory for your brushes (i.e. PSBrushes).
2. Unzip the brush you downloaded. Open your file directory and drag and drop the brush file.
3. In Photoshop, select your brush tool. Open the brush preset picker and click the arrow. This will drop the brush options.
4. Select
Replace Brush. Go to the folder that you saved the brushes in and double click on the brush you want to use.
5. Start using your brushes.
Repeat the same steps for every time you change your brushes. If you want to go back to the default brushes, just open the brush preset picker again and select
Reset Brushes.