a little fedora help

[Collins Richey]

Just for grins, I decided to put up a copy of FC3. Install seemed to
go ok, and I've got a usable copy of firefox running, which means I
have email. FC3 didn't setup my sound card, which is not too
surprising.

I thought to see if there were any updates, so I ran

yum check-update (ran ok, list of updates produced)
yum update (failed with the following:

You have enabled checking of packages via GPG keys. This is a good thing.
However, you do not have any GPG public keys installed. You need to download
the keys for packages you wish to install and install them.
You can do that by running the command:
    rpm --import public.gpg.key
For more information contact your distribution or package provider.

OK, so I did 
rpm --import public.gpg.key

This failed with:
error: public.gpg.key: import read failed.

What do I do?

TIA,

-- 
 Collins