When you are on the page in question (with the Howdy chips), go to the top of the screen where the URL is shown. Left click in the box to select the URL then right click and select Copy.

Underneath where you are posting to the BB there is a box marked Optional Link URL:. Select the box next to the message and paste in the link that you had just copied.

In the box marked Optinal Link Title, type eBay Auction or whatever.