Some suggestions for the first time user. Additions and corrections welcomed. Please be sure to read about revocation before you leave.
pgp -ks [-u yourid]
pgp -kxa
"Help! I've lost my passphrase!" "My key's been compromised!" "My secret key's been destroyed, and there's no backup!" "Someone made a fake key for me and is circulating it on the keyservers!" [The first case is by the far the most common.] These explanations usually accompany a request to disable, remove, or revoke a key on the keyservers, because the key is now invalid.
The only practical way to deal with the invalid PGP key problem is to create a key revocation certificate in advance. Please read the instructions. (This is taken directly from the comp.security.pgp FAQ.)
pgp -kd youruserid.
pgp -kxa youruserid.
This file is what the manual calls the revocation certificate.
Why? Key removal is useless, since the key can be recreated and/or uploaded at any time. Revocation is possible only so long as you know your secret key's passphrase. Disabling a key is possible, but is impractical; it will only happen if you are personally known to us, or someone makes us an offer we can't refuse. Disabling keys is a service that is more appropriate to a key certificate authority (which you are, in a sense, for your personal keyrings). Please read the help file. The keyservers are not certificate authorities and can take no responsibility for the contents.
Another viewpoint on the same topic, from the MIT keyserver.