How do heterotrophs get their energy?
By consuming organic matter.
A heterotroph is defined as "an organism deriving its nutritional requirements from complex organic substances." So, humans and most animals are heterotrophs. By consuming organic matter and breaking down that matter for energy. Heterotrophs can NOT produce their own energy, and completely rely on consumption of food.
An autotroph can make its own energy synthetically by using simple ingredients in its environment. A plant, using photosynthesis, is an autotroph. Sunlight is the simple ingredient. It takes that simple ingredient and creates energy with it. If you are ever confused between the two, the prefix "auto" means "oneself", if you can't remember that just remember that autotrophs make their food automatically.