Find the appropriate forum for what you'd like to post a message about. Click on that forum (ie ONEcnc), and find the button on the left hand side of the screen near the top. Fill out the subject line and message box, and click submit.
If you'd like to reply to an existing thread, click on a subject line (ie. "having trouble with my software") to read the existing posts, and find the button that says . Type your message, and click submit.
You may also scroll to the bottom of the page where it says "Your Reply" to type and submit your message.
Please note you must be a memeber and LOGGED ONTO the site.