Greetings. I am arriving in Shanghai (PVG) Terminal 2 on 31 Jul 2016 at 20:30 Hrs.

Well, the last train departs from Main Railway Station at 21:08, so I am afriad that you cannot catch it.
Therefore, you may take metro line 2 from PVG to the downtown area, where you can see the Bund, Huangpu River, and Xintiandi. On the next morning, you can take a high-speed train to Beijing from Hongqiao Railway Station. The first train departs at 06:39, and the trip takes about 5.5 hours. :)

Thank you very much.