It almost sounds like you are looking at a "sample" instead of the "full" library.
What happens if you right-click on one of the tabs way down at the bottom where they all tend to bunch up and overlap each other?  Do you get a flyout menu?

Actually I tried placing a WF beam from the Design Center and discovered that when I select it, I get a drop down menu to choose the size I need. That will work for now, but a "full" Library would be nice. Steel joists are not one of the options so I'm going to wing-it! I don't normally do structural; I'm usually modeling corridors and the usual Civil stuff.