Polish fireworks best fireworks.
But on a more serious note, Fireworks are at the end of the day explosives. You wouldn't set a chunk of C4 off in your hand, so why do it with a firework?
I hope you've sought medical advice as from the picture that looks like a partial to full thickness burn, and considering its on your fingers you could potentially be looking at nerve damage. I hope it heals soon and you learn a lesson from this.
My friend's neighbors were playing with Cobra 6's.
As stupid as they were, they threw one right in a pit which had a gas main running through.
You might know what happened next, of course, a part of the gas main blew.
My friend's dad called the firemen, they came, solved the issue.