On Walkadoo, you can send a cheer to any member who has not yet completed the current day's step card. When you send someone a cheer, they receive an email and/or push notification letting them know you've encouraged them to complete their step card for the day. You can send up to five total cheers per day (you cannot cheer on the same person more than once per day).
To cheer someone on, visit their profile page and click the orange "Cheer on" button in the top-righthand corner. At this time, cheers can only be sent from the Walkadoo web site, and cannot be sent via the Walkadoo iPhone or Android apps.