So, you need to tunnel Remote Desktop, and your servers are all set up, right? Good.
Now get Putty.exe for you client computer from HERE and run it.
Fill in your IPCop's host name or public IP and then change the port to 222.
Next, expand Connection, then SSH and select Tunnels.
Add a new forwarded port source 3399 (since this one isn't commonly used) and forward it to the target server's internal IP (NOT the IPCop's IP!) and add a :3389 to the end of the string as in the second figure.
Go back to Session, click Save, and give this connection a name. Click Open, and you will be prompted for a username and password - give these (preferably the remote user we created earlier instead of the dangerous root user) and you will get a prompt. You're done with Putty for now!
Now go to Start, Run, and type mstsc.
Fill in the Server line with localhost:3399 and hit connect. If all been done correctly, you will get a remote desktop on your target machine.