how do you lot make fireworks in minecraft?

Star effects if you want more than plain colours: a fire charge gives the large ball, a gold nugget the star shape, a head the creeper face, a feather the burst. diamond adds a trail, glowstone adds twinkle. you can stack the extras onto one star.

paper and gunpowder and that's a plain rocket. one gunpowder flies low, three flies high, and that's all the gunpowder count changes. colours and shapes need a firework star first - gunpowder and a dye - and then the star goes in with the paper. if these are for elytra boosting, leave the star out, the bang takes a chunk off you.