Before starting Access

[ParisaMoosavi]

Hello

I have developed a access programm which contains a central mdb database and each user in the network has its own mdb file. Users run their access file and this access file linked to another access file which is central database. Now I need to do the following:

I want if the central access file is used by user A, the user B can't run its access file. How can I do it?

Thanx