Mac OS Install Disk Disk Image

my install disk is really scratched can i make a disk image i case the disk gets any worse
how do i make a disk image

You can do this in Disk Utility.

First, launch Disk Utility and mount the CD or DVD. Select the disc from Disk Utility’s left column. Then select File: New: Disk Image From name of disc. A Save dialog box appears. From the Image Format pop-up menu, select DVD/CD Master. Click on Save. After Disk Utility has created the image file, select Images: Burn. In the dialog box that appears, select the image file and click on Burn. Insert a blank disc when prompted.

That will allow you to burn a new bootable copy.

And to add to Kevriano's splendid answer, if you are using Leopard or Snow Leopard on a full retail install DVD, always helps if you provide that information, use Apple System Profiler to ensure you have a Dual layer burner and use DL media if necessary.

If you wish to copy disc one or disc two from the original system, proceed as advised.