Calm down, you came to the right place!
Probably you have a modem configured as a bridge, it just means that the signal is just converted to ethernet packets and send to your interface, and it also means that the authentication is made on your machine.
when you execute the pppoeconf
you create a configuration file for a dialup connection authenticated.
You could create the configuration file manually, but pppoeconf is our friend and make this process easier.
The configuration file created is stored on /etc/ppp/peers/dsl-provider
(at least on my machine, Debian 6, but on Ubuntu it should not be different)
if this file do not start automatically when you init your machine you can put the ppp interface up with the command pon
on my case it is:
the connection need to be authenticated so some times it take a little long to put the interface up, it do not means that the command did not worked.
to close the connection you can use:
I recommend you read more about the TCP/IP and PPP
this forum is a good place or newbies, don't be ashamed to ask, but you have to make your homework before.
Please don't go back to XP!!