For some clearance:

Jedi=Good

Sith=Bad

Remember this because it is important for understanding the story.

Chapter 1: Early Years

Anakin was once just a teenage Padawan who wanted to be a Jedi knight just like his friend and mentor, Obi-Wan Kenobi.  

As he began to mature, he was able to become a Jedi knight, just like Obi-Wan and he got stronger with the force. He was one of the best Jedi knights when it came to protecting, especially when his girlfriend, who eventually became his wife, was attacked. With the help of Obi-Wan, they defeated the enemy. 

Protect me Anakin!

NOOOOOOOOOOOOOOOOOOOOOOOOO

Anakin started to have nightmares and visions of his wife passing. 

Chapter 2: The turning point

Anakin found himself with Darth Sidious, a powerful Sith lord, but he didn't know that it was him. He told Sidious about his visions and Sidious told him he knew someone who could stop death. The thing that Anakin didn't know was that the guy Sidious was talking about is dead. 

Sidious told Anakin he would teach him how to stop death, and Anakin took the chance. Little did Anakin know, Sidious actually taught him the ways of the Sith.