Terminal Services or VPN

We are launching a new POS software and the company does not support a multi-location practice. They did go as far as to recommend using termina services as the method of allowing the remote office to access the data on the server. I have static IP’s in each office and I think I can setup Terminal Services, but I dont know how to set it all up to allow 2 people in the same software (being that my boss is cheap and is using the server as a workstation for the software as well)