.net code for changing passwords

hi
i need a .net function (preferably vb.net, but C# will work as well) that accepts the name of my server (on the LAN network) , an admin username and password
and iterates over all the users on the server
and changes their password to "MYPASS123"

pseudeo code sample:

function ChangePasswords(Server as string, username as string, password as string)
connect to {Server}
dim users=list of server.users
for each usr in users
usr.setpassword("MYPASS123")
next
end function

thank you!