If anyone has seen the walking dead series, how did everything begin?

I've wanted to see the show from the beginning but I can never catch the re-runs. I've only seen tonights show. How did all hell break loose in the first place or did it even tell that part of the story?If anyone has seen the walking dead series, how did everything begin?
No, it is never explained what happened. After getting shot, the main character just wakes up in the hospital. Signs of gunfights, chaos and carnage everywhere. Half eaten corpses on the floor and blood smeared on the wall. When outside he sees abandoned army operations and vehicles. Hundreds of bodies littered on he floor. He goes home, a man and his son find him, they help him. He goes to Atlanta to find his wife and son. Gets jumped by the undead horde and seeks refuge in an abandoned tank. There the first episode ends.If anyone has seen the walking dead series, how did everything begin?
Erm I seen it from when a cop got shot. Woke up in a hospital. Blood everywhere and there was nobody alive around