My previous question was closed so I will be more specific.
I need to create an application, desktop one written in C#, that will ask for user credentials and after verification opens the GUI allowing to work with DB (black box for users). It should be used from everywhere, not LAN or SQL domain. I assume I would need to do the following:

1. Create a client and a server applications that will deal with authentification. That would mean a lot of socketing stuff..
2. Once the user is verified, the client queries would be sent to database (client->server->DB).
3. The server would need to send the DB data sets back to the client.

As you can see, this is just my guess but I have no idea whether its too complicated or completely wrong. The main thing is that it must be desktop app (not web based one) and accessible from everywhere.
I am interested in main points how to design the system and will be extremely grateful for that.