There is full documentation about Remote Desktop connections in Help and Support.
To enable it, if you are currently logged on as the administrator, go to Access Sytem Properties in Control Panel and click the Remote tab.
From this tab you can enable both Remote Assistance and Remote Desktop.
Once you have enabled it there are two matters to weigh up. First is a user account with the remote computer having to log on to your computer with ausername and password, just as if it was your own.
Logging on locally a blank password can be used, but Remote Desketop connection requires you to have a password. You have to consider the account to be ong on with a ensure the password is configured for it.
If it isn't, you can configure one using the User Accounts option in Control Panel - you may want to create a specific Remote Desktop account just for the connection as well.
If you have the Internet Connetion Firewall enabled and not configured to pass Remote Desktop traffic, it will not work. Configure ICF to pass the RD traffic on the Services tab of its Advanced Settings window.
From this point you should read up in Help and Support (key in Remote Desktop Connection into the index) to determine what users are being allowed to connect to you from a remote computer.