[Wine] Using .sign PGP/GnuPGP/gpg

[Dee Ayy]

I have never used PGP nor GnuPG, but I understand that it has more
features beyond using say MD5 to verify my downloads.

I noticed Wine has a .sign file (i.e. wine-0.9.40.tar.bz2.sign for
wine-0.9.40.tar.bz2).

I installed http://macgpg.sourceforge.net/ (which has an MD5 for
download verification), and since I never used PGP/GnuPG, the
instructions seem to just say to create a keypair, which I did.

How do I verify my wine download?
Whether I use:
gpg wine-0.9.40.tar.bz2.sign
or
gpg --verify wine-0.9.40.tar.bz2.sign wine-0.9.40.tar.bz2
I receive:
gpg: Signature made Fri Jun 29 12:38:13 2007 CDT using DSA key ID B9461DD7
gpg: Can't check signature: public key not found

Do I need to get a public key from the download mirror server?  How?

Regards.