If you are new to extension development with VS Code and the AL language, you might want to practice this first. There are various resources out there, but a very comprehensive one, though not too voluminous, is Dynamics 365 Business Central Development Quick Start Guide by Stefano Demiliani and Duilio Tacconi.
Here is a link to the Packt page where you also can order the book: https://www.packtpub.com/business/dynamics-365-business-central-development-quick-start-guide