Just click on the "Envelope" icon in the upper right of the main menu of the game if ever a red dot is present. 

If videos are present, simply click on one of them, wait for the loading of the advertising screen and watch it all the way. After that a window will indicate the amount of tokens earned. 

It may happen that there is no video to watch. In this case, it means that the inventory (that is to say the number of videos we offer our advertising partners) is exhausted! 

PS: The number of videos as well as the amount of the reward can vary over time. The ad is seasonal, so it depends on the frequency.