Fan Forum is divided into different boards (like the Newbies board or, say, the Alias board) and each board is divided into threads (which are different topics where people comment and discuss things, like this is a thread destined to Questions and Answers but we also have another one dedicated to the Introductions or even dedicated to games). Threads are divided into posts, which is what each member replies to the one above.
You posted a reply into a thread, but if you wanted to open a brand new topic to discuss what you liked, you'd open what we call "a thread".
I hope I explained myseld clear enough
Let me know!