User passwords

I am trying to set multiple users on the same computer,
with different logons. I have just gone from cable
internet, back to dial-up. 1.) How do i enable all users
to use the same dial-up connection without having to
install it on all user accounts and 2.) I have set the
main connection up for dial-up. When trying to connect to
my other logons, i can access all but one. My users all
had the same password, as I hadn't changed them. How can
i check to make sure what this users password currently is
or to see if it has been changed or can i? I would
appreciate any and all help, and please explain step by
step if you can...I'm new to this =) Thanks!!