The library view is where you can browse all of your photos. You can adjust thumbnail sizes, change views, add captions and ratings, and so on. When you hover your cursor over a thumbnail, a translucent bar will appear, which you can click for additional menu options. This menu is shown for the first thumbnail in the screen shot shown here.
Looking in the left column of this screen shot, under "Other Sites," you'll see that Photoshop Express can hook into other online photo services so you can work with your images from those services directly. Currently, Facebook, Photobucket, and Picasa are supported. Adobe has stated that Flickr is coming next, and other services will be added based on user feedback.
I'll show you more on how this works a little later in this tour.