You are going to want to use the B/S/T forums. Go to the main pbnation page and scroll down until you see the B/S/T forums. Go to the correct forums for your stuff, create a new thread just like you did here.
Take a ton of pics of your stuff, host them on a place like imgur.com, and post links to the pics in your thread. Give as much info as possible, don't lie about stuff (that's called fraud and has real consequences), be honest when people ask questions. Try to list a price (add "or best offer" if you are willing to negotiate), it helps weed out the people who are going to try to grossly lowball you.
Get a paypal account if you don't already have one, people like using paypal because it offers a safety for them and you. Also, don't be stupid and send your stuff without payment first (unless they have a good reason to), look at their feedback (avoid people with any negative feedback).
You have enough posts for private messages so use those when sending people private info like emails, phone number, etc.