How can I bookmark and follow different forums??

To bookmark and follow different forums, select one of the three buttons here.

You can either Subscribe, Subscribe to OP or Bookmark.

Subscribe: Anytime anyone posts on this thread you will be notified.
Subscribe to OP: Anytime the original poster posts on this thread you will be notified. For example, you are the Original Poster (OP) of this thread.
Bookmark: You will not be notified when someone posts on this thread, however, you can access it under 'My Bookmarks'.

Keep in mind, you can only find these options for subscription/bookmarks on the first post. :)