Hhow to make backup OS X Install Disk?

I have a G4 iBook, 37.3 B Toshiba MK4025GAS. How do I back up the OS X Install Disk 1 to another disk? I have been trying but the computer doesn't take dual layer disks and the single layer isn't large enough. The size of the original is 5.3 GB. I made a disk image and selected "compressed."