If you bought your own postage, you need to finalise the transaction now only on the Seller Hub here:
https://www.ebay.co.uk/sh/ovw
Go to Orders >> Awaiting Postage, click on the item then top left on View Order Details.
Far right from More Action drop down menu click on ' Mark as Dispatched' if you have it, add any tracking number there too.
@5001chrisa