User names and passwords on a network

What is the most straightforward way to deal with usernames and passwords in my app? I have a contact database and each time a letter is sent out I want to attach the name of the 'sendee' to the contact record without them having to enter it each time, so do I use HKEY_CURRENT_USER and if so how?

You can create a simple log on screen and cross reference this against an employee table.

All you need to do is then save this username in a variable and then reference this each time a contact is made.