how to configure PPP and MacTCP?????

[mp@onion.it (ok)]

I have a big problem!!!
I can't connect my Mac to Internet.:-(
I installed MacPPP and MacTCP but after a long series of failure attempts
in configurating that tools,i'm still out of the Net.
The Error which appears is something like that:"insufficient resources..
.. or network down".
Can anyone help me?

                                      Thanks
                                               Franco