To upload pictures you must first create an album. 

On the Home page or on your profile page, hover over the "Applications" tab and drop down to "Photos."

Here you will see previously uploaded photos and have the ability to create a new album by clicking on the "Create Album" link.  You can choose the name of your album and, if you wish, you can give a brief description of the photos included in it.  Once this is completed click on the "Create Album" button at the bottom.