I see on the comm tab that you can send a message, and that all messages are public. Where are the messages displayed publicly?

Anybody that can see the ship a comm is posted on can read that comm. For example, if you post something on my ship comm, anyone that sees my ship can read the message.

Thanks for the info. How can you post to a member or alliance that you are not allied with? I was told to go to a certain alliance and tell them I was sent there by another stronger alliance. It was their "farm" alliance. I requested to join, but I don't know how to contact them.