sudoers file??

I am trying to connect to postgreSQL through PHP. I am 
facing lots of problems. Itried to configure postgreSQL 
for the above purpose.I tried the following command to set 
PGALLOWTCPIP=yes


sudo vi /etc/postgresql/postmaster.init

It says : postgres is not in sudoers file.
What does it mean?

Can I get some tips on how to use pg_connect in PHP. I 
tried every option in this but its not working.

Looking forward for some tips from your side.
Thanking you.

Vivek C. Shidhore
email: vivek@fideltech.com