Like most serious gardeners, I love compost. Compost is decayed plant material. Mixed with the soil, it improves both the composition and fertility. Plants grow the best in soil with lots of organic material like compost.
There are a lot of resources on the web for creating compost and they can do a better job of describing the details than I can, but basically you put dead plants, vegetable kitchen scraps, grass clippings, leaves, etc. into a pile. Avoid putting in meat, bones, diseased plants, or weeds with seeds. Ideally you can mix green and brown material (dried leaves and plants) in layers. Keep it moist and if the pile is big enough it will start to heat up from microbial activity. The material will break down over a period of weeks or months into a dark crumbly material that is ready to mix into your soil.
Turning the pile frequently and keeping the optimum mixture of green and dark material will produce finished compost more quickly. Frankly, I don't worry all that much about it. I am fortunate enough to have a very large compost area. That lets me be lazy and the material I put in this year will be ready next year.
In the fall I pile all the finished and partially finished compost into a pile on one end of the compost area. I have a lot of maple trees in the yard. They produce a lot of leaves in the fall. I till a 3-4" layer of leaves into the vegetable garden beds, and the rest go into the compost pile. They don't do much there in the winter. I continue to add vegetable kitchen scraps though out the year.
In the spring the leaves will be compacted and wet. Left in that state they might take a few years to break down. I pile them to the other end of the area away from the now finished compost started the previous year. As the year progresses I add green material in the center of the compost area. After I have a few inches of green material, I add a few inches of the leaves. This continues until all the leave are used up.
I try to turn the pile a couple of times in the remaining part of the season. By early fall, last year's compost is used up and I move the pile from this year to one end to start the cycle again.