In this tutorial, we will make a fireworks animation using After Effects. Some points to note
1. When you duplicate a pre-comp, make sure to do it from the projects panel so that the changes made to one pre-comp is independent of the others.
2. Using Cmnd/Ctrl + → moves the indicator by 1 frame and pressing Shift with the combination moves forward by 10 frames.
3. The overall rotation of the second layer is changed by half of the repeater rotation so that it fits between the first layer animation. You can also make one more duplicate with rotation turned to 15 and move it forward a couple of frames.