The cell membrane is a phospholipid bilayer. It has two layers of phospholipids, each phospholipid has a hydrophobic (water fearing) and a hydrophylic (water loving) head. The tails come together to stay out of the water making the membrane. Also, there are several proteins embedded in the membrane (some have carbohydrate tails attached) and cholesterol sometimes to maintain the fluidity of the membrane. Here is a good picture www.soulcare.org