Rewarded Ads offer a voluntary way for you to view advertisements that support the game in exchange for receiving some money in the game. At the time of writing, you can receive up to $2,000,000 per day for your nation from watching Rewarded Ads, at $80,000 per ad watched.
To use Rewarded Ads, click the link “Rewarded Ads” in the sidebar (or mobile menu) under the Nation heading.
Once on that page, you will be able to click the button that says “Begin Rewarded Ad ($80,000)” which will begin loading the video ad. It may take a few seconds to load.
Once the ad is loaded, you will need to watch the whole ad. Sometimes, a “Skip” button will appear (like on a YouTube video) but if you skip the ad, you will not receive the reward in-game. When the ad is finished, it will automatically close out and you will see a notification that you have completed the rewarded ad and have been credited the $80,000 bonus. If you refresh the page, you will see that you have received a notification detailing this as well, and the money will have been added to your inventory.
Alex has created a video demonstrating how it all works that is available here: Click to go to YouTube video, and is embedded below