If you install the script file and Photoshop actions as instructed below, it should work out of the box. It is meant to be run by using one of the ready-made actions that comes with the script file, or by a droplet made from one of those actions. It will automatically apply a border, the style of which depends on whether it’s a 2:3 image, a 4:3 image, a 6:7 image, a 4:5 image or a square image.
If you want to, you can stop reading after the installation instructions below and start playing with the actions, or you can read on and learn how to create your own actions, batching folders of images and troubleshooting.