How can I use the screen of a broken MacBook?
Imagine building yourself a monitor, and the only part you have is the screen display itself. No input port, controller circuitry, nor power supply.
There are not going to be easy steps that you can follow unless you can determine the OEM of the panel and dig up a kit and guide to provide a display assembly that drives that LCD panel.

Use MacBook Pro LCD Screen as a standalone monitor
Can my Macbook Pro&#39;s display receive inputs from other sources?