The host PC needs to have the Openstream app installed and a public IP address (most ISPs give a free static and public IP address) then ask your friend for the IP. When you have it, install Moonlight on your PC, then pair your computer and the host PC together using a code provided by your Moonlight client. After pairing, you can control the PC, and make sure to change the resolution. You can do that or use Parsec which even allows you to play together just by being friends on the app. This app is free and only somewhat buggy.