For each site on which you want to place ads you need to define one or more ad locations, referred to as Spots.
A spot can show a single ad, or it can show up to three different ads, selected in rotation.
A new spot called Spot 1 is created, and the Settings tab lets you choose which ad or ads to show on the spots.
The pop-up menu will list all your ads, plus the ads from anyone you have listed as your associates.
The ad will be shown on the Settings tab:
In a similar way you can up to two more ads to the spot.