I've found a windows NT program, but how does it work?

I'm on a windows NT network (unfortunately with minimal user access)
But it does have VB 6.0 on it!

There's a program that looks like a primitive VB application.
It has a button that gets you a list of the usernames of the users logged on.
You can then select the user and send them a message.
Or you can view their screen and control their mouse and keyboard.

As a challenge, I've decided to write a similar program, but have gotten stuck.
Can anyone help me? I'd really appreciate it.

you didn't say how far along you are. I know that an application like that would require the winsock control so you might start your search there.