Here is a little tutorial for turning a PNG file into a digital element in PSE. Maybe there is an easier way, but this is how I figured it out and wanted to pass it along.
Click on each image to make it larger and it will show each step.
open a new file
look for your downloaded PNG file
it will open in a new window
under the edit tab, click define brush
i leave it titled as is, you can change it if you want
there is your brush!
then you can open up your photo and apply, change the color, the opacity, just have fun!
I hope that helps and please feel free to ask me any questions!