To get to the second gym in a typical Pokémon game, you'll need to progress through the story, complete various objectives, and defeat the first gym leader. Each game has its own unique story and progression system, so it's important to follow the specific instructions within that game.
If you're playing a fan-made game or a custom ROM hack, you'll need to consult the game's specific guides or documentation for information on how to progress through the game and reach the second gym.
Could you please provide more context about the game you're playing? If you tell me the specific game name or a bit more about its content, I might be able to provide more relevant help.