To edit your profile go to "my settings" at top of page. To the side you will see a link that says "edit my profile".
To post on a thread, first make sure that the thread is not closed. If it is, no one else can post in it. It will say "thread closed" at the bottom. If it is not closed then just go to "reply" on one of the posts and you will get a box to post in. There should also be a box to type in at the bottom. After you type your response just hit submit.
Welcome to Bluelight!