I start a new thread (=topic) as follows.

(a) I go in the main menu to Community > User Forums.
(b) Under the title 'Web Design Software Discussions' I choose the section ( i.e 'Welcome to the Forums' 'Responsive Site Designer' etc.) in which I wish to start the new topic.
(c) At the left, under the heading 'Forum Tools' I select 'Start New Thread'.

Having started a new topic, it's worth clicking on 'Subscribe' at the top. While one is subscribed to the topic/thread, one gets an email whenever someone adds a post to that thread. Failure to do this has led some to miss out on helpful replies to their problems. When one is subscribed to a thread, the button at the top shows 'Unsubscibe' instead of 'Subscribe', and so one is not left forever receiving such emails.

If the above doesn't work for you at present, it should do so after you purchase CoffeeCup software.

Frank