Backstage structure and organization

I'm struggling to find out how to organize different type of resources in Backstage. I want to make backstage for company where we need to track following resources:

• Templates. To quickly bootstrap ready code
• Libraries. Simple npm package which will be used in projects. Just a link to github repository and documentation
• Projects. Company has many projects. Each project has separate github organization and repositories inside. I'd like to list all projects in Backstage including information about them like link to github organization, repositories, documentation, etc

I have no problems with templates, because backstage has a good documentation about that, but I don't understand what's the right way to register libraries. Backstage has kind Component, but I'm not sure whether is right way to use it for libraries. And I have no idea how to handle projects part. How can I connect github organizations and list all available projects with linking to github organization.

Could someone just point me out to any kind of documentation or examples?

A Component is indeed the right kind of Entity to hold a Library. A library is a particular type of Component (other types are website and service) - see docs here.

Depending on what a Project really is, Backstage may or may not be an appropriate tool to manage it. If a Project is a chunk of work, with tasks, deliverables, and deadlines, then it's not really within Backstage's remit - Backstage aims to catalog Software entities, and a Project (in that sense) is something that's completed with Software, not a thing that is Software. However, if you're using the word Project to describe a collection of related Services and Resources that together accomplish a particular goal - a sort-of "higher-level service" - then that fits the description of a System or, possibly, a Domain.