To set a promoted mission, please follow the following steps.
1. After you create your mission, scroll down to the Reward section and select the Eaves Reward (Scaled) reward type. (Note: you can also select the Vees Reward tab also if you want to offer vees instead of eaves).
2. Select the reward you want to give.
3. Then navigate to the Promote this Mission section and check the Set as Promoted Mission box.
And thats it! You just set your mission as a promoted mission! Make sure you save your mission or publish it as soon as your done!