I'd love to say I made them from scratch out of only gradients and paths, using my super-professional skillzzz, but really this is what I did:
1. Found 4 different free stock images from dreamstime and stock.xchng of fireworks. 2. Created a 2500x2500 document in photoshop and imported one of the images into it and resized it and such. 3. Spent the next 10 mins editing them (erasing the background junk, making the firework better looking etc.) 4. Selected all with control A and saved it as a brush preset.
I did the same pretty much with all 4 of them. I wish now that I'd made more of them - do you know if you can edit submissions to DA?