Hydrogen is formed into helium, and helium is built into carbon, nitrogen and oxygen, iron and sulfur.
When stars get to the end of their lives, they swell up and fall together again, throwing off their outer layers. If a star is heavy enough, it will explode in a supernova.
Sums up the fact that the carbon, nitrogen and oxygen atoms in our bodies, as well as atoms of all other heavy elements, were created in previous generations of stars over 4.5 billion years ago.
Our atom is similar to the atom of stardust, Which means half of the human atom comes from stars.