You can upload photos simply by clicking on the PHOTOS tab in the menu above. The system "remembers" that you are the one that added those photos and organizes your photos into a slideshow if you choose. That slideshow--with the photos you choose--will appear on your own page. You can also share that slideshow on your page on any other site on the Web where you can paste in the code for the player.
You will see almost everyone's photos streamed in a slideshow on the front page of the network (unless you choose to not have yours shown--click on 'edit properties' for each image you upload).
You can also insert images into a document such as this. Hypothetically then, you could insert an endless series of images into a text box such as this and have a static photo gallery in addition to a photo slideshow, if that is something that interests you.
Finally, you can upload a document into your text box...it creates a link to a document that is then hosted on the Ning server. Note that once you change the contents of that text box, if you remove the link the document will be lost.