Luckily, Microsoft has put together extensive documentation for VS Code — which Next Code is based on — already! Here is some you may want to check out.
The official documentation contains a getting started guide, overview of the interface, details about support for various programming languages, and much more. It also includes links out to all the other documentation resources.
There are introductory videos for:
Who doesn't love tips and tricks! Check them out in this section of the documentation.