upgrading linux redhat

i am running redhat 8 i want to upgrade to redhat 9 if i put in the cd will it automatically upgrade.

HELP !!!

thanks

g's thanks for all the comments_old to my question they are all being taken on board for me to consider..

take care :)

late comment..

I think the full replace is the better option aswell. The way I do it is have my /home (user data) on a different partition to the rest of the system. Then.. when I upgrade I don't overwrite /home.. the rest can be formatted..