if you wish to reply to a post that someone has made you can do this one of two ways.
if you wish to answer someone in particular, hit the quote button to the right of the post, this will copy what that person has said and then you just add your reply to that and hit send at the bottom of the speach box.
if youd like to have your say but indirectly, just hit the quick reply button at the bottom of the last post, type in your message and hit send.(or use the post reply button at the top left of the page)
if youd like to post a new topic (other than what is already available in this forum) then hit the new topic button at the top left and type in a title and add your message or topic to the box that comes up , when your done, press( send or post ) at the bottom and your done.