To protect your photos from screen capture, first open an album in the Organizer and then click Customize Album.
In the Privacy and Settings area you can add Screen Capture Protection, which overlays your SlickPic url at the top and bottom of your image.
When users see the image in your gallery they will see it with your personal SlickPic url overlayed, so that if they try to take a screen capture it will be clearly marked as yours.
Note that watermarks can also be used to protect photos and are a better option if you want to put a customized signature or logo onto the image. However, this setting is the quickest and simplest option.