Formation
Stars begin as cloud of dust and gas called a nebula. Gravity causes the cloud to collapse as particles move faster the temperature reaches millions of degrees. This stage is called a Protostar.
Main Sequence
If the temperature get high enough hydrogen fuse to form helium. This fusion releases a huge amount of energy. Stars can stay in the main sequence for a vey ling time.
After
Stars
At some stage the hydrogen runs out/levels get low. Then the outward force due to fusion is less than the gravitational force so the star collapses inwards which causes the temperature increases now helium can fuse to create heavier elements - however only lighter than iron. And the star expands to form a Red Giant. At some point fusion stops. Then the star shrinks and becomes a white dwarf. Without fusion it calls down and eventually stops releasing the energy and becomes a black dwarf.
Stars
At some stage the hydrogen runs out/levels get low. Then the outward force due to fusion is less than the gravitational force so the star collapses inwards which causes the temperature increases now helium can fuse to create heavier elements. And the star expands to form a Red SUPER Giants. Then when fusion stops the star explodes - this explosion is called a Supernova. The temperature of a supernova is high enough to produce elements heavier than iron. When it explodes the elements are distributed around the universe.
Depending on the mass the supernova can either form a Neutron Star which consists of densely packed neutrons or a Black Hole