Animating multiple flights must be one of the most entertaining things you will be doing with SeeYou.
By default the Play button will start to animate flights in real time. That is, positions of the gliders will be the same as they were in real flights. You can see who was following whom and where the other competitors were when you had that stonking lift.
That is however not the only way to look at a day of flying. You may wish to organize a Maggot race where everyone starts at the same time. In an animation like that you can clearly see who was in the front at each moment of the race. Some preparation is necessary:
1. You need to Create the task everyone was flying.
2. You need to select Animate > Synchronization > Start time. The list below the selection box should give you the start times of everyone you are animating.
3. Press the Play button and everyone will leave the start line at the same time.