Create YAML script under “CREATE NEW SCRIPT”. How exactly?

Configuration
1

I would like to create a script under “CREATE NEW SCRIPT” under Scripts that sends a GET command:
http://192.168.178.45/relay/0?turn=on

How does it work? What exactly does the complete YAML script have to look like?
Do I have to enter something in the file: /homeassistant/configuration.yaml? If yes, what?

2

The first step is going to be setting up a service that sends your command.