Gravity pulls dust together so it forms a protostar
Protostar n. an early stage in the evolution of a star, after the beginning of the collapse of the gas cloud from which it is formed, but before sufficient contraction has occurred to permit initiation of nuclear reactions at its core.
As the protostar gets denser and denser, it forms a star
as the star becomes older, it becomes a red giant
red giant = star uses up its energy and becomes cooler, so it expands
Layers of the red giant fall off, releasing dust and gas into space.