Just click to edit the capsule then type in your keyword on the textbox under the eBay search. Click the preview button to see what item has been found.
If you don't like the item being shown or if it's not the right item, then just adjust your keywords accordingly. You can add a minus(-) next to a word so that it will not appear in your search results.
Alternatively, you can use the seller ID to search for eBay items. If you click the help tab beside the item selection tab on the capsule, you can get more tips and tricks on what to do. Hope this helped.