Unless it's different for the first post in a thread (been a long time since I started a thread) ........ If you go to the post you want to delete/edit, at the very end of the post, in the right-hand corner, you should see hyperlinks to reply, edit, delete, or flag (with the flag grayed out as it's your own post). You'll need to of course be logged into the account you posted from.
(Otherwise, you'll probably have to contact a mod. I have no idea which mods, if any, are active on the board right now.)
(Otherwise, you'll probably have to contact a mod. I have no idea which mods, if any, are active on the board right now.)