I can't find Blaine to get the volcano badge.?

Get the Secret Key from the Pokémon Mansion and enter the Gym. You will need to either answer the quiz correctly or fight to go from one stage to the next up to Blaine.

Blaine is on Cinnabar Island but to open the doors you need to find a key in the fire place left to the gym

First you have to go to the building to the left of the gym. You have to go through it, and you'll find the key to the gym in there. Then go to the gym. You can choose to answer questions there, and if you get them wrong, you have to battle trainers. When you get to the final room, Blane will be there.

You have to get the secret key in order to get into the gym.

You get the secret key by getting through the abandoned mantion right next to the gym.

Don't forget to take the quizes inside the gym so you don't have to fight the trainers.

Happy gaming.

Blaine is located on Cinnabar Island, which is best accessed by Surfing south from Pallet Town. Look for a large plot of land to land on. Unfortunately, to get into Blaine's Gym, you must obtain the Secret Key from the burned out lab to the left of it.