4runnerman,
That's it. The whole shebang. Buy those parts, read about/watch videos, put the right parts together, and you have an AR.
ARs break down into several sub assemblies. The two main ones are the upper and the lower. The lower is serialized, controlled by the ATF and other law enforcement agencies. It includes the trigger group, a buffer tube, stock, and the housing for all of those parts. An upper binds to the lower via two pins, contains the barrel, handguard, and the Bolt Carrier Group (or BCG, as it is commonly known).
To assemble an AR typically involves putting an upper and lower together, setting the two takedown pins, and voila, a rifle. This particular upper comes without the BCG and charging handle, both of which slot easily into the back of the upper without tooling.