Script writing comes in steps.
First step: Find out how many Acts do you want. Acts are like if you've ever seen a stage play. Usually there's three of them. Act one is the beginning... there's a break between...called Intermission. Act two is the middle also known as the heart of the action or drama. Finally Act Three is closing or wrapping up of the story and what happens to the characters and all that.
Every movie follows this template. Same for TV and webcomics. Webcomics however differ in nature because it's more of an ongoing story. The Simpsons doesn't follow this template because well, it's just not easy being thirty plus years on TV. So most TV shows follow this.
I've always wanted to write a TV show. I sent my script to two people who were in the industry and nothing came of it. I even sent it to two animation studios. Nothing came of it. I don't get discouraged... I just keep writing and I would like to help you do the same.