How do I landscape my backyard?

I want to create a garden of perennials, shrubs, etc paired with my already existing japanese Maple tree. I don't know where to begin. It is in my backyard. I live in Sinking Spring, PA. and my backyard is facing-South on a slight slope. I would like to have a plan to give to a local landscape company to cut out and create a garden around my Japanese Maple tree. I would love it to be local, native plants, with lots of color for all seasons.