We are trying to use this as a platform for user generated content. How do others share their photos in my gallery?
When you set up the gallery you can decide if other people should be allowed to upload to a gallery. You simply need to provide them with a link to be able to upload through. So the way you would do this is:
You can also set up sharing outbound in the same gallery settings.
More info is available at http://help.smugmug.com/customer/portal/articles/526320-can-guests-upload-photos-to-my-site-