Problem with authentication in psql.

Hi everybody,
   I have some problem with the Postgres user authentication. A user
with password was created by me, but when I tried to enter in psql using
that user I received a fail mesage.

$ psql -W template1 pagano
Password:
psql: Peer authentication failed for user 'pagano'
   Anybody knows what is happening?

Thanks for all.                           Vitalino.