Organic matter is transformed into compost through the work of microorganisms, soil fauna, enzymes and fungi.  When making compost, your job is to provide the best possible environment for these beneficial organisms to do their work.  If you do so, the decomposition process works very rapidly--sometimes in as little as two weeks!  The trick to making an abundance of compost in a short time is to balance the following four things:  Carbon rich materials, Nitrogen rich materials, Water (moisture) and Oxygen.

Carbon:  Carbon rich materials are the energy food  for microorganisms.  You can identify high-carbon plant materials because they are dry, tough, fibrous, and tan/brown in color.

Nitrogen:  Nitrogen rich materials provide the protein-rich components that microorganisms require to grow and multiply.  Freshly pulled weeds, fresh grass clippings, over-ripe fruit and vegetables, kitchen scraps and other moist green matter are a good source of nitrogen. 

Water:  The right amount  of  moisture is important for the composting process.  Too much moisture will drown the microorganisms, and too little will dehydrate them.    Your compost pile should be kept about as moist as a well-rung sponge.  If you must water the pile, insert your garden hose into the middle of the pile in several places, or sprinkle the pile with water then next time you turn it.  Using an enclosed container or covering your pile with a tarp will help you to control the correct moisture level.

Oxygen:  Microorganisms require a lot of oxygen , in order to work efficiently.  When your pile is first assembled, there will probably be plenty of air between layers.  But as the microorganixms begin to work, oxygen will become depleted.  You must turn  the pile periodically or the microorganisms will become sluggish.