Hi and welcome linkman.
To sell you need to be a paid member. I believe that it is a fiver or tenner (3 years). Have a look at the subscriptions tab at the top of the page or the link in my signature below. It may be worth joining just to get the plate up for sale. Paid members get access to additional threads including discounts and offers. At the moment there are links to discounted Oxford Monster locks, discounts for powersportplus, Busters, M&P, Powerbronze, oils etc.