have you read this article already? First steps - where do I start, where do I begin? It explains pretty well how to set up everything and also how to send encrypted email to other people than yourself. Considering you managed to do that already, You can start with the How to find your friend's public key section. You need the other person's public key in your keychain to send them encrypted emails. This can be done in different ways. They can either give it to you on a usb thumb drive or anything like that or attach it to an email they send you first. They can also upload their key to a keyserver (like you did) so you can add their key with the GPG Keychain app by searching for their name.
Remember to never ever share your private key and to secure it with a sufficient password.
Steve on 14 Jan, 2019 08:03 PM
please excuse the late reply. And thanks a lot Bennett for chiming in. There's not much to add to your reply.
Joshua, if you are able to send yourself encrypted and signed messages and decrypt and verify them when you receive them, your setup is working fine. Once that has been established the requirement to send encrypted messages to others is indeed to have the public key for their email address.
Let us know how this goes and if you need further assistance.