Garageband - Youtube: Making simple music from scratch tutorial

For my completed film I will need to create music that will be suitable for its theme. To do this I may choose to use Garageband. So I decided to watch a YouTube tutorial on how to create music using the programme in a simple way that will let me produce music to a high standard.
In the tutorial it shows you step-by-step ways on making and setting up you piece. It shows you simply how to make music using their already built-in instruments and manipulating them to suit your tastes..