If you have Static IP and be able to ping, than everything is OK, else you have to install Hamachi.

Click here and download. The installation process is straightforward. Once Setup have completed, Hamachi detects if you are running the program for the first time and runs a Quick Guide, for new users to acquaint themselves with the program basics. By following this guide, you will be set up with a Hamachi address.
Once Hamachi is installed, you will see its application files in “C:\Program Piles\Hamachi”.

Then,client have to join network. On a computer other than the one used to create the network, click on the Networks button. In the menu that appears, select Join existing network.

The Quick Guide gives you an example network to join; however, in the above example, the name and passphrase of another network: Network_fsb, have been entered. Enter next data :

Network Name : xxx

Network NPassword : xxx

The next step is to select Join. The network then appears in your UI network field, showing that you have joined it. If your other clients are blue or green everything is OK. If they are yellow shutdown your Hamachi and download this file. Run it, let it complete and re-run Hamachi. Restart Hamachi few time if necessary, until status is green or blue.

Now ping other users by clicking on their name in dialog. If that works than you can start using MS Windows Remote Assistance.