Locking a Database

[Grafilo]

I have a database that is intended to be used by one user at a time. Occasionally another user may use it in which case they get an error message about saving. Is there a way to set a lock on it so that if a user is already in the database it simply won't let anyone else open it until they have finished? Kind of getting a message saying that it's available as Read-Only.

Any advice?

-Gina Grafilo