This script is meant to be used with a crop event. That is the easiest method.
Set up your crop event. Then when you crop an image Photoshop will automatically save two copies to a folder the script creates. The folder will be created in the users My Documents folder and the script will save a jpeg and png. If you have made part of the image transparent in PS, the PNG will have transparency. The only thing I have not been able to figure out is how to get the script to save with soft edge transparency.
You can use your own path if you like, just change cPath. I wish I knew how to make an installer file that would set up the crop event, but I don't so you are on your own with that.