A nebula is a cloud filled with dust and gasses that are pulled together from the force of gravity. The stellar nebula that has appeared from the White Dwarf. A new star will form from this nebula.
Massive Star / Supergiant
After millions of years, the dust and gas gets pulled together causing a sphere filled with gases. This star becomes a prostar and stays in this phase for millions of years
I am so bright now!
After the prostar was formed it formed into a massive star. It will start to lose more and more hydrogen, then it nuclear fusion will begin.
After nuclear fusion, and the loss of hydrogen, the star collapses. This later leads to the star becoming a supergiant. The star emits heat and becomes extremely hot.
I am a star!
Part 2 - Supergiant
The star is getting closer and closer to the end of it's life. But before that, the star becomes a supernova. Since it's last form was a supergiant, it will become a supergiant instead of a regular nova.
The final stage happened when the core is swallowed by its own gravity. After the explosion, gravity's force doesn't let protons and neurons combine and then a black hole appeared.