If you mean the MC Library files, moving those to a NAS isn't a good idea. You would see a large slowdown of MC, because it is constantly accessing its Library. Reading and writing to a NAS over a network just isn't that quick.
In fact, the recommendation is to have your MC Library on the fastest local drive your PC has, preferably an SSD of some form.
The is also the problem that if you move the Library files to the NAS, and more than one PC tries to use that Library at a time, you will break your Library. The MC Database stored in the Library isn't a multi-user database. It can't have two PCs reading from and writing to it at once.
The best way to have three computers using one Library is to designate one computer as a MC Server, and have that Server available and running, or sleeping and able to be woken, whenever one of the other PCs run MC. In that case, when one of these MC Clients runs, a copy of the MC Server Library is sent to the MC Client, and then change are synchronised between the two. There are some limitations on what a MC Client can do, for example it can't move files around on the NAS using MC functions, but in terms of playback, tagging, etc., it does the same as the MC Server.
The Wiki has articles on Media Server, Media Network, and so on that explain how to do that.