Accessing Glow in PS, PS CC, and PSE:
After launching Impression as a standalone editor, it will become available in your Photoshop Filter menu (you may need to restart Photoshop).
If not, please see here on how to access it there:
Important: Your image will need to be 8 or 16-bit depth in RGB color mode. You can change this via Image > Mode in Photoshop.