Upgrading from 10.04 32 bit CD

[Geoffrey]

I have obtained a Lucid Lynx CD from Ubuntu-AU, and it has installed
successfully on my brand new and PC. The home directory from 9.10 has
been installed on 10.04 from an external HDD.
Now I am trying to upgrade from 9.10 to 10.04 on my old PC, so far
unsuccessfully.

With the 10.04 CD in the CDRW drive I find that I can only boot up on
9.10. There is no automatic response from the CD and the boot list only
refers to versions of 9.10.
I have inspected the contents of the CD and I read the INSTALL folder
SBM file, but I can't see how that will help.

So, how is upgrading with the 10.04 CD done?

Geoffrey