Hi, this is my first post and I can’t seem to find the answers I’m looking for so I decided to write my own scenerio and hope someone can help!

In my back room, I have a light switch that operates my back room light. I have no porch light outside. I am wanting to have two switches there, one for the original light and one for the new porch light. The original switch only has 1 BLACK, 1 WHITE, and 1 GROUND coming in. I’m guessing the power was taken to the light fixture and not to the switch since there aren’t more wires coming in. How do I pigtail off the original switch to have power for my new switch to operate my new light? I hope this makes sense. Anything will help. Thanks!