If you wish to start a new topic, simply navigate to the forum with the category most relevant to your discussion and press the Post Thread button in the top right corner of the page.
Enter the title of your thread – this is important, as this is what people see to decide whether they want to read your discussion. Try and make the title descriptive of what your discussion is about. Though note that any tactics to try and make your thread overly standing out, such as excessive emoji’s or UPPER CASE, may mean that your thread title be edited.