The previous app we were using to remotely access PCs (LogMeIn) got rid of their Free Edition so we decided to find a different solution.
On the remote PC, ask the person to install a Chrome browser extension called Chrome Remote Desktop. You will have to follow the same installation procedure on your PC (the computer you will use to connect to the remote PC).
On the remote PC, instruct the person with the remote PC to follow these steps:
1) Open Chrome browser.
2) Launch "Chrome Remote Desktop."
3) Under "Remote Assistance," click the "Share" button.
4) An Access Code will be auto-generated -- ask the person with the remote PC to send you this code.
6) On your PC, click the "Access" button and enter the code that was created in Step #5.
The code is unique so each time you need to connect to a remote PC, you will have to follow these steps.