@SvitlaAngel Basically, here is a Charged Creeper farm... Netherrack squares (5x5) with a hole in the middle, Ill say how to get Creepers in later. In the hole, made of Glass (I prefer Glass, so you can see which one is charged... duh...), and a worthless material under so you can knock it out later when you get a Charged Creeper in. When the Charged Creeper is dropped (from the box) it will go in some kind of transportation (4th picture). If you have Creepers in, AFK during a thunderstorms a good 30-40 blocks away, so Lightning can strike
How to catch Creepers: Put trapdoors on the holes and lure them, they'll think the trapdoor is a block and walk over it, they'll fall in(Make sure to remove trapdoor before use, or it blocks the Lightning. Make sure to name the Creeper, so it won't despawn.
Have some kind of chamber where the Charged Creeper is met with another mob (Creeper, Zombie, Skeleton) and then blown up with Flint and Steel. Make sure to hit the mob you wanna blow before having the Creeper come in, the Creeper's damage doesnt kill it. If the mob is successfully killed by the Charged Creeper, it will drop its head (Does not work on Players! Dont try...)