You can check if there is space available and upgrade to Top Spot by following the steps below,
1. Click on the "Promote" icon in the left navigation panel,
2. Select the "Top Spot" checkbox,
3. To complete the Top Spot upgrade, select "Checkout",
*Please note, if you already have an Ultimate Boost in place on a stock item, you will need to wait for this to expire before applying any further promotions to the item.