First, you have to be in a topical forum or sub-forum in order to start a new thread.
#1) Click on the "Forums" Tab at the top of your screen
#2) Find the "Airstream Forum" topic that best matches the subject of your question, click on the title (For example: On the Road, Interior Restoration, Trailer Forums, etc.)
#3) See if you can narrow your topic within a sub-forum, if so click on a sub-forum title (For example: "On the Road > Full-Timing" or "Interior Restoration > Plumbing" or "Trailer Forums > Argosy Trailers")
#4) Click on the "NEW THREAD" Button
#5) Follow the prompts to submit your new thread
Once it is submitted, it will show up on the "Portal" or "Home" page for all to see. It will NOT show up as a "new post" to you until someone adds a comment.