The footer will contain pagination if ever you have more images than the current allowed space for SharinPix can handle.
Each thumbnail allows you to select an image (using the check box upon the thumbnail).
Clicking on the thumbnail allows you to view the image in its original size.
When the album is empty, the thumbnail view is turned into a drag and drop area.
When the album host images, you can still drag and drop images on any blank part (around the images).