SanYeo,
What you are trying to accomplish should be fairly easy. However, I'll need some details in order to help out.
I'm assuming that you are going to write the program in VBA, since you've posed the question here. My concern is that VBA must be hosted by an application and can not be a stand alone executeable. So, I'm wondering, what is the host application (i.e. Word, Access, PowerPoint, Excel) for which you are writing this program? Also, are you writing a server/client program? It would of course be much easier, you have a main program running in the background some where checking user access.
Let me know, and I'll keep checking the thread. Have a good day.
Bernie