On this page:
When viewing your own pictures or the pictures of another user, hovering over a picture provides an option to View image which provides a larger view of the selected picture. If viewing one of your own pictures, additional picture options are included with the larger view, such as Remove picture and Set as profile image.
The Add picture panel at the bottom of your gallery provides a button for choosing a picture to upload, and a second button for uploading the picture to your gallery.
When viewing a picture, you have the option to Remove picture from your gallery.
When viewing a picture, you have the option to Set as profile image the picture being viewed. This option will replace any existing profile image with the chosen gallery picture.