Hello And welcome everyone today I’m going to show you how to setup Windows Remote Desktop please note this can not be done on every windows version! Please see the ‘Supported Systems’ Link below on Microsoft their site.
Video: 
Guide:
1- Open your Windows(Version 7/8/10 ‘Control Panel’.
2- Click on ‘System and Security’.
3- Next Click on ‘System’. (In Windows 10 This is the 3rd option)
4- Once there you will see your system information now in the left portion of the window you will see a few options Click ‘Remote settings¬’.
5- Make sure ‘Allow remote connections to this computer’ is checked.
6- (RECOMMENDED) Check the box ‘Allow connections only from computers running Remote Desktop with Network Level Authentication’ as well! (this is for your own safety)
7- Now we need to port forward port ‘TCP: 3389’
8- This may vary depending on your router but its similar on every router to check how to port forward your router check: https://portforward.com/router.htm can be handy and if you know how to port forward just port forward TCP port 3389 on your INTERNAL IP(to find open CMD and type ipconfig and search your ipv4).
9- You will also need to allow a connection in your firewall (SEE VIDEO)
10- When done you can go to this link to get your EXTERNAL IP http://www.whatsmyip.org/ your IP will be shown on top of the page
11- Now go to another Windows computer search for ‘Remote Desktop Connection’
12- In the box ‘Computer:’ type your EXTERNAL IP
13- Click ‘connect’ and a box will appear and now just log in with your computers(the one you are connecting to) Credentials(Username and Password)
If This didn’t work you may have port forwarded wrong if you need help you can reach out to me anytime! Also Check if your computer can be used for remote access With the Supported Systems Link https://docs.microsoft.com/en-us/windows-server/remote/remote-desktop-services/clients/remote-desktop-supported-config
If you have any questions feel free to ask them