I got two errors!

[eluser]Mohsen32[/eluser]
Hi,
I've just finished the developing stage and now it's time for setting up everything in real environment.

I uploaded everything but I got these two errors:

A PHP Error was encountered
Severity: Warning

Message: Cannot modify header information - headers already sent by (output started at /home/user/public_html/system/application/config/config.php:1)

Filename: libraries/Session.php

Line Number: 662


An Error Was Encountered
Unable to load the requested file: helpers/mp_common_helper.php


any help?

btw what is best chmod for php files?