It's simple. You need to copy ABR file (it contains brush presets), open "Brushes" folder of your Ps (Photoshop > Presets > Brushes) and paste the file. You don't have to do this but it's good to have all your brushes in one folder.
Then open Photoshop, select brush tool, open predefined brush presets (I guess it's a correct name because I don't have english version), click Load brushes and just pick the file you pasted before. Maybe it looks complicated but it's very easy
Try to experiment with making your own brushes. You can find many tutorials about it on YouTube I hope I helped.