Summary
In this hour, you downloaded and installed the GNU Privacy Guard, or GnuPG or GPG for short, a free implementation of Pretty Good Privacy (PGP).
You learned to create your own public/private key pair, import and export public keys, fingerprint new public keys for verification, and sign keys that you can positively verify. You learned to indicate to GPG whether signatures from other users whose keys you have on file ought to be trusted as though you had signed the keys yourself.
Finally, you learned to actually use GPG to sign messages or data using your private key, to verify signed messages that others have sent you, to encrypt outbound messages that are for the receiver's eyes only, and to decrypt inbound messages that are for your eyes only.