PHP Directory Permissions on Linux (aka dumb newbie question)

Hi folks, Here's a dumb question (I'm a complete idiot so please forgive). I installed the PHP4 as a module to Apache 1.3.12 on my Red Hat 6.2 box. I want to be able to manipulate some files with PHP, but only in one directory, and I don't want other users in there (other than myself). So far the only way I've been able to allow PHP to work with the files is by setting the permissions so everyone has complete access to them. I'm thinking I need to change ownership of the files or maybe change the group they belong to, but what user or group? I've also installed MySQL 3.22.32, but I haven't done anything with it yet. Am I going to have to revisit this issue when I start using MySQL? Possibly related Apache is started on boot by root and several httpd process are run by a user called nobody (BTW I never created this user). MySQL is also started on boot by root and the mysql processes are run by my userid. Do I need to change any of this? Thanks, -Leonard