Facebook has an ads api but that covers posting ads on facebook itself for your app. What you want is to place ads from a third party in your app? I think there are some nice plugins over in the completed plugins forum to interface an ad program like Adsense. If you have a particular person looking to place an ad though, that's simple. Add the browser plugin to your app first. Then ad a sprite plugin and use the ad image for the sprite. Now inside of an every tick event, add a set opacity to 50 for that particular sprite. Now ad a condition below the on tick event that sets the opacity to 100 when the mouse is over it. Ad a mouse on click event so when the user clicks the sprite the browser plugin will open the advertisers link in a new browser window. I'd offer an example capx but I'm away from my computer so I can't access c2 right now, sorry.