You can connect to any gaming PC that you have access to through the Parsec application. Unfortunately, however, it's really difficult for us to choose reliable settings that work for everyone due to the variability in networking, hardware, wifi, routers, and peer-to-peer connections. For that reason, you should fiddle with the settings on your client to improve the quality of your connection.
Your computer settings are found by clicking the gear link in the upper right corner of the Parsec application. From there, choose your computer settings. Then you can choose from any of the settings listed in the computer tab. These settings apply to the client only, and they determine the quality of the Parsec stream.
For multi-player co-playing, please remember that all video settings are determined by the first person to initiate a connection.