Fedora core 8 - how-to change video screen resolution?

Someone

I am using Fedora core 8 which I installed in a virtual machine on my Mac
Mini using Parallels for Mac 3.0. I was successful in getting the OS
installed and operating but I can't figure out how to go about changing the
screen resolution so that it uses my entire screen while running. Currently
it is only using about 60% of the screen. BTW, trying to use alt-F in
Parallels does not allow the desktop to expand to full-size (ie. change to
1024x768 resolution.)

I have tried checking the documentation that came with the OS and also
documentation online but was only able to find a document that suggested
that I needed to change 'screen depth' resolution in the Xorg.conf file
found in the etc/X11 folder from '24' to '16' and then reboot which would
allow the OS to use the full-screen. I tried the steps in this document but
it did not work.

Does anybody know what I need to do to change the screen resolution? What
file do I need to modify? what changes do I need to make to this file to
get Fedora to show the desktop in 1024x768 resolution?

Thanks

Chris