cron to change owner of file

recently I emailed my webhost, contacting them about CHMOD'ing a .php file to 777. the method i was using the CHMOD was the php function chmod(); which did not work
the server provider then contacted me saying that i had to run a cron that changes the owner of the .php files every so often. i have a few questions

1. what is a cron (because i feel as a web designer, even though this is a one-project problem, it is better to gain more and more information)
2. what would that be, keep in mind that i do not have shell access and that i have to implement them through cPanel's cron interface
3. what would i have to change the owner to? the login to my server is "octopi" however, would there be a unix preset name?

1. From http://www.unixgeeks.org/security/newbie/unix/cron-1.html:
   
   Quote:

   Cron is the name of program that enables unix users to execute commands or scripts (groups of commands) automatically at a specified time/date.

2. You need to create a shell script that does the CHOWN which is run by CRON.
3. If you want to do the CHMOD with a php page of your web site, you need to change the owner of the file to the user the apache web server is running. You can get this user by running a php test script.

If the problem is that you only need to CHMOD some files you have uploaded to your site, you can do this using ftp. Most ftp clients let you execute CHMOD on remote files.

ok, so what would the cron be? i'm a little confused. on my interface i'm running, there are drop-down boxes that handle all the times and such, but there is a line for a unix command to run. if you wrote a script cron.sh, what would you do to execute it?