How to make an Update Program Function???

Hi all,
My boss has just asked me to make an "Update Program Function" for our program.

My program is being used by someone in my company. The database is put on server computer.

At the present, my program run by some dll file, and when I fix or update the source code, i will compile to dll and put it on the server disk. After that, the users will go to this server disk and copy the new dll and overwrite the old dll in their client computer.

Now my boss asked me to make an "Update Program Function" : before the user login, the program will check the version (or the creation date) of the dll in the server disk, if it newer than the current dll, the program will update the new dll, else the program login normally

How can i do that?

Please show me how!

pls help me

Basically have a version number stored in the DLL. Then on startup check a file on the server to see if there is a newer version. If so then download it. I don't see the problem? Basically all you are doing is automating what the users already do?