Sending a message
When you are subscribed to a list, you receive all messages subscribers send. You can reply to those messages or send some yourself.
Sending a message with an email client
To send a new message, it is very simple: from your email client or a webmail, send a message to the list address. This address consists of the list name followed by the suffix '@lists.thekeyboardcowboys.org' (example: psycho_cognitive(@)lists.thekeyboardcowboys.org).
Be careful: you need to send the message from the address with which you subscribed to the list, otherwise, your message might be rejected.
Sending a message from the mailing list environment
You can also log on to the mailing list environment, go to the information page of the list to which you want to send a message and click on the 'Post' link in the left menu.
This method is not very flexible: from the mailing list web interface, you can not add or change some recipients, add an attachment or format the messages you send.
Replying to a message
To reply to a message sent to a list, do as for any message that would have been sent to you in private. However, be careful: some lists are configured to send any reply to the list by default, i.e. to all the subscribers. If you only want to reply to the message sender, make sure the recipient of your message is the right one!
You can also reply to a message directly from the mailing list environment. However, it is far simpler and more functional to reply using an email client or a webmail...