Before and After

To get the picture I’m using click here.

Step 1
First click your brush tool or just click B and pick out a round brush. Any round brush is fine.

Step 2
Have your settings set to:
Size: 171
Hardness: 12
Don’t worry about the other settings.

Step 3
Make a new raster layer set to screen at 100%. And now you can start using different colors on your picture. The best colors I’ve found to work with this is blue and pink.

Step 4
After adding your brushes, duplicate that layer and set it to Soft Light at 20%.