Based on information you gave it’s really not possible to give a detailed answer.
Here are some issues that would have to be checked first:
Which version of VB have you used to write this application (I assume that .NET environment is not used?), and if there is a data base attached to this application, which data base is it?
Then you would have to plan how to provide access to external users. I mean what kind of server will be used, how will the server be attaced to Internet (speed, firewall), how to offer secured access to the server (VPN?), etc.
Techinally it’s possible to install a VB application (I’m talking here about VB6 and older versions) on a local machine and use the application to access a data base via Internet on a remote server.
Depending on application design this can be pretty fast or then very slow. I would need more info about your application in order to give better advice.