Remote Connection to Network

We have a Windows NT server, with a small office LAN. about 12 computers connected. We bought 2 more stations. These will be set up in other 2 buildings, in different locations. We want these stations to connect to our server. What is the best option/way to accomplish this?
I am not very knowleadgeable on Networks, I am a programmer, so please explain in detail.
Thank you in advance.