I must preface this with the confession that I have not been a good compost-bin caretaker. I pretty much just throw whatever we have into the bin and ask my husband to turn it once or twice a year. Right now it is overflowing with all the perennials I pruned last week. It is, however, a great place to dump all the yard waste, prunings, spent garden plants, weeds, kitchen scraps, corn husks, etc. Any spilled dry dog food is also good, as it contains a high amount of nitrogen. You should not add sticks, eggs, meat, or kitchen grease.
To make a free compost bin, we used three pallets nailed together. You can typically find free pallets at warehouses. Sitting on their sides, they form a three-sided compost bin.