The script comes with a number of ready-made starter actions, grouped by aspect ratios. Open an image in Photoshop and explore them! The actions contain recipes (script settings), that determines the look of the rendered border. As a default, the images won’t be saved after the script runs, leaving them intact. Because of this, the actions won’t work for automation (such as droplets) just yet. If you make a droplet at this stage you’ll be prompted to save the image on every droplet run.
When you’re ready to have an action save the resulting image, or when you want to edit the recipe of an action, expand the action (click on the right bracket) to show the recorded script name, Poserframes. When you double-click on this, a dialog will open where you can edit the saved recipe. Click the button labeled Use this recipe to save your changes. Sometimes Photoshop acts a little finicky and does not save the updated recipe, especially if you edit many actions one after another. If that happens, try closing the image you have open, open it again and then edit the action.
If you check Save and close when done the script will start saving and closing the image after it runs, so leave this unchecked while you’re still trying out different recipes.