How do I make a user's session time out after an hour of inactivity?

Hello Drupal Community!

Thank you for taken the time to look at my question. I am a completely new Drupal user and I have much to learn.

As I understand it, my page's session-time-out setting is currently set to default (23 days) but I would like to reduce it to an hour. I don't know how to do this.

I have experience with HTML and some experience with Java...

I found this page:

http://drupal.org/node/590832

I found the file by going through cPanel, but when I tried making the change, I got this error message after trying to save:

open settings.php failed: Permission denied at cpanel.pl line 667
	Carp::croak('open settings.php failed: Permission denied') called at /usr/local/cpanel/Cpanel/Fileman.pm line 1139
	Cpanel::Fileman::fmsavefile('%2fhome%2fmounta11%2fpublic_html%2fsites%2fdefault', 'settings.php', '<?php^M^J// $Id: settings.php,v 1.39 2007/01/14 02:05:15 unconed E...', '', 1) called at cpanel.pl line 667
	main::__ANON__('%2fhome%2fmounta11%2fpublic_html%2fsites%2fdefault', 'settings.php', '<?php^M^J// $Id: settings.php,v 1.39 2007/01/14 02:05:15 unconed E...', '', 1) called at cpanel.pl line 1789
	main::exectag('<cpanel Fileman="fmsavefile($FORM{\'dir\'},$FORM{\'file\'},$FORM...') called at cpanel.pl line 4808
	main::dotag(undef) called at cpanel.pl line 4691
	main::cpanel_parseblock('SCALAR(0x91a0700)') called at cpanel.pl line 4643
	main::cpanel_parse('GLOB(0x94d78f8)') called at cpanel.pl line 1318

"...Permission denied..." ...strange because I was logged into the site using the master account.

I feel that I need some detailed instructions...

Would it be possible to have a separate value for average users and another value for Administrators? I would like them to be able to be logged in for 23 hours.

Thanks a bunch!

Larkale07