Problem with compiled C

Hi , I have two problems.

1. When a use pgacces, i try connect with one database, responde the
next error.
Error trying to connect to database "xxxx" on host "xxx"
PostgreSQL error message: Connection to database failed
connectDB() --connect() failed: Connection refused Is the postmaster
running (whit -i) at "xxx" and accepting connections on TCP/IP por
"5432".

I use Postgresql 6.5, on RedHat 6. I don't know why not connect.

2. When i compiled one program in C, I don't Know what parameter i use
with gcc
but i compilied the example of the testc.c in manual of programmer no
indicate How to compiled.

Thanks for yor help.