MOD MAKERS NEEDED

I need a program that can make me create my own mod. Im on a mac so find something for me. Telll me a program and I'll give you some diamonds :)

I was inspired by the Aether mod and created my new dimension. I have some related objects to the Aether mod, such as ability to get clouds, but in a different way. There are dozens of new mobs and more ores. There are more stronger materials like falcite, (falcon ore) ruby, and more! These are just ideas, the mod isn't started yet. I NEED A MOD MAKING PROGRAM FOR MAC PLEASE!!!!