how do I get more brushes

There are quite a few brushes and brush presets within Photoshop.  See screenshot.  Click on the Brush Tool's GEAR icon for more options.

That said, I have acquired many great specialty brushes online.  But making my own custom brushes is way more satisfying & well worth learning. 

Nancy

Search google for Photoshop brushes. You will find tons of sites offering brushes.

If you want creating your own brushes look here: Create and modify brushes in Adobe Photoshop