If you live on a farm in the middle of nowhere and just feed all your kitchen waste to the dog or put it in a giant pile half an acre away, then congrats! You’re composting for free.
If you live in/near a town, you have a little green bin inside your house which you fill with kitchen waste then cart outside and dump in the giant green bin (which contains all the other yard waste) and the waste collection truck empties your big bin into their even bigger bin. Then it goes to a local farm to help grow the food you eat.
The part that costs money is the bag you put inside your little green bin (or you don’t and just wash the muck out every couple of weeks, congrats, free). To make the bags for free you need your weekly flyers or newpaper, an empty stamp booklet and your pile of left socks.
Make a little bag by following the instructions in the link of My Newspaper Subscription and My Compost.
Use the sticky part that surrounded the stamps as tape to hold the flap down. Put a sock in the bottom of the bin to absorb miscellaneous goo and put the bag on top. There you go, free!
Line flyers on the counter when you’re peeling potatoes, carrots or eggs to catch all the peelings. When you’re done just toss the whole mess into the compost bin and you won’t have to pick wee little carrot shavings out of the grimy sink.