Composting is a great way to reduce waste going to landfills, and creates your own natural “fertilizer” to return carbon and nutrients to the soil and feed your plants.
Composting involves taking vegetable and fruit scraps (apple cores, banana peels, cut broccoli stems, etc.) and grass clippings, which are the GREEN components, and mixing them with dried leaves and twigs, which are the BROWN components, in about 50/50 amounts. Add some aeration and moisture, and let the organisms such as bacteria and fungi, as well as worms and insects, do the rest! Bacterial decomposition (breakdown) of the green and brown materials will heat up the pile, and the fungi, worms, and insects will all work together to further decompose the compost into a simplified, organic product that resembles soil.
You can put the compost materials in a durable, sealed plastic composting bin, or you can even make your own open-air bin made of chicken-wire, wood, or other materials. The advantage of the sealed, plastic bins is that they are animal-proof, which is essential in not attracting unwanted critters such as raccoons, skunks, and possums to the food scraps. The open-air bins can still be utilized with select items such as leaves, twigs, and grass clippings.
Composting outside in this area of Illinois can be best accomplished during warmer months when the bacteria, fungi, worms, and insects are more biologically active, generally April through October or November.
https://www.epa.gov/recycle/composting-home
https://extension.illinois.edu/compost/process.cfm
Get your science on! https://web.extension.illinois.edu/homecompost/science.cfm
Backyard composter with Ruby throated hummingbird visiting Cardinal flower. 
Backyard composter surrounded by Native Plant garden
Composters like the dual-chamber, rolling one shown above, are a little higher in cost, but can be helpful in “cooking” the compost, or breaking down the organic matter, more quickly. The dual-chamber is helpful by letting one side “cook” and not adding material to it, while adding fresh compost materials to the other side. If you have a single-chamber composter, you can fill it to about 2/3 full, then you need to wait until it is mature compost (crumbly, brown, soil-like) before harvesting the compost and starting a new batch.
Trouble shooting: Compost too wet, mushy, or foul-smelling? Add more brown materials. Compost taking too long to break down? Add more moisture and/or green materials.
AVOID THESE ITEMS IN COMPOST: Meat, dairy, fat drippings, pet waste, yard waste treated with chemicals, diseased plants, weeds, and ashes. NOTE: Weed seeds, mold, and other undesirable biologics can survive in a compost pile if the temperature is not high enough, so it’s best to leave them out unless you track the temperature. http://compost.css.cornell.edu/physics.html
Where do I get a bin? Big box stores and online sites sell many types of compost bins. The Lake County Forest Preserve Native Plant Sale on May 11th and 12th, 2019 in Independence Grove will offer composters and rain barrels.
How much do Plastic Composting bins cost? Approximately $50 to $150. They can last many years, and therefore be a low-cost addition to your yard in the longer term. The cost is also offset by not needing to buy expensive fertilizers or bagged compost.
Can I compost inside? Yes, with smaller bins including Under-the-sink composters and Vermicomposters. Vermicomposters utilize worms to break down the green and brown materials. Indoor composting does still need an area to receive the finished compost, and should minimize unpleasant odors in the home.