Problem in postgresql installation

Hi=20

I have installed a 7.1.3 postgresql version on my linux server.=20
When I type "createuser xxxxxxxx" it asks me :  Shall the new user allowed =
to create databases (y/n)?
                                                                        Sha=
ll the new user allowed to create more new user (y/n)?

I answer yes to the both questions and then a bug report said : " psql : co=
nnetDbstart()  -- connect() failed - no such file or directory
                                                                           =
                 Is the postmaster running locally and accepting connection=
s on                                                                       =
                          Unix socket :'/tmp/.s.PSQL.5432'
                                                                           =
             createuser : creation of user 'xxxxxxx' failed.

Thanks for your help.
Mr Paquin