This forum system is based around the Markdown system for text layout. Specifically it uses the Github flavour.
You will notice that it has more of a chat feel about it. Much of the forum use is discussions between two people with maybe a third interjecting every so often. A chat-like environment is more atuned to those kinds of discussions.
To start a new topic just click "New Topic" in the top bar. From there you can select the forum you want to post in. That will start a new discussion about whatever topic you want. You get to ask your question or post your main information in the question box when creating the topic. This information remains separate from the discussion, and is what the discussion is then about.