Your message is hardly to understand but if you ment:
"How to setup php.ini to use a remote server for sending emails"
Then i could answer your question.
Just open the [mail function] section in your php.ini and follow instructions.
As you can see it's 75% Windows OS only and you said it's a Linux server, so there's not much need to change it.
The linux server should have a sendmail application.
If doesn't then you should look into
http://phpmailer.sourceforge.net/