Where to find "php.ini"

I wanted to upload a picture with a new entry to the guestbook. That didn't work. In the EasyAdmin it says: "To use this upload feature you have to turn SAFE MODE off in your php.ini".
But where can I find that - php.ini - actually ? Checking my server with FTP it is not there. It should be under the admin directory of guest, but it isn't there.

How and where can I turn of that safe mode and be allowed to upload pictures to the guestbook? Can anyone advise at ppep@loxinfo.co.th ? Thanks

regards
Frank