Flash powder is the universal composition for almost all pyrotechnic reports. Bottle rockets, thunderbombs, m-80's, shells, everything. If it is not enclosed in a container then a bright flash along with a lot of smoke will be produced as shown in the picture. If it is enclosed in a container, even the smallest amounts will produce a loud report and a violent explosion.
If you are going to use this to make fireworks please note that fireworks must be legal in your state, you might need some sort of license, and that you can use no more then 50 milligrams per firecracker ANYWHERE no exceptions. Any firework that contains more then 50 milligrams is illegal in every state.
Flash powder was originally used for producing light for cameras about 100 years ago. You have probably seen something to this extent where a photographer holds a wooden handle with a flat platform on top, says look at the birdy, and poof he ignites the flash powder.
There are many different formulas for flash powder, I will explain the simplest one with the easiest chemicals to get your hands on.
Step 1: Chemicals
400-600 mesh aluminum powder. The mesh refers to the size of the particles in the powder, it may also be referred to by its actual particle size in microns. For micron size the smaller the number the smaller the particle, for mesh size the higher the number the smaller the particle. A general rule of thumb - the smaller the particle the better. Can be bought on e-bay.
Potassium perchlorate - it is the oxidizer in the reaction. It is getting harder and harder to come by, the CPSC is trying to outlaw many different chemicals, and potassium perchlorate is high on their priority list. As of this writing it can still be bought on unitednuclear.com.