Most PGP/GnuPG reviews/howtos I've seen start with long description of public key cryptography and instructions on key generation.
And that's the problem.
(I've been using PGP/GPG for 20 years and I still use a cheat sheet).
hack (Hæk) vb. 1. to write computer programs for enjoyment. 2. to gain access to a computer illegally. ~n 3. one who works hard at boring tasks. 4. a mediocre and disdained writer. 5. an old or worn-out horse.