It is made of a long chain of nucletoides, which have three parts: a base (there are four kinds, as people have already pointed out), a phosphate group, and deoxyribose, a type of sugar.
The four bases are ring or double ring molecules that include Carbon, Hydrogen, Oxygen, and Nitrogen. They are sometimes called "nirogenous bases," but I don't like this because nitrogen, while present, is a pretty small fraction of these things.
The phosphate group is a phosphorous atom bonded to three oxygen atoms.
Deoxyribose is a five carbon sugar, made of carbon, hydrogen, and oxygen. The carbon atoms form a ring. Most edible sugar contains six carbons. Sugars generally have a ratio of 2 hydrogens and one oxygen for each carbon atom, which is why they are called carbohydrates, even though they don't contain water molecules.