Here's how they do it:

* Photosynthesis: The most common way for autotrophs to make food is through photosynthesis. They use sunlight, water, and carbon dioxide to create glucose (a sugar) for energy and oxygen as a byproduct. Plants, algae, and some bacteria are examples of photosynthetic autotrophs.

* Chemosynthesis: Some autotrophs, like certain bacteria, don't use sunlight. They use chemical energy from inorganic compounds (like hydrogen sulfide or methane) to produce food. This process is called chemosynthesis.

Let me know if you'd like to know more about photosynthesis or chemosynthesis!