Hello Graham and welcome to Seven Forums.
I agree, sometimes instructions can be very confusing. I'm going on the belief that you're using the native (built in) Windows 7 backup utility. I'm also guessing you're using disks to create the backup. Or, perhaps you're also creating factory recovery disks for your HP computer.
These tasks usually require that multiple disks be created. If you ever have to use these disks, they need to be used in the proper sequence. So after a disk is created, you usually get a prompt saying "Label This Disk Backup 062612 # 1" or some such thing. Then you'd put in a second blank disk, wait for the backup utility to do its magic, and then you'll get another prompt to "Label This Disk Backup 062612 # 2" and so on and so forth until all disks have been created. If you ever need to use these disks you'd start with # 1. After the computer reads the data on # 1 it will eject it and prompt you to insert # 2, etc.
One caution: do not use any kind of sticky paper labels on the disks. They can peel and destroy the CD/DVD optical drive or the glue can damage the disk. Use a CD/DVD marking pen. Hope this helps.