The Big Bang is the belief at all matter in the universe was squished into a small space. and exploded, and the dust that exploded from the small space became all the planets, stars, etc. Some text books actually say nothing exploded and became everything. Evolutio needs to be defined, there are 6 different types of evolution:

Cosmic--origin of space, time, and matter
Chemical--origins of elements
Stellar--origin of stars and planets
Organic--origin of life
Macroevolution--animals change to different kinds if animals
Microevolution--variation within the kind

The last one is the only one that has any sort of factual evidence. But they use that one to try to prove the other 5.