The Packages is where you have an overview of Components and files that can be used to build your integrations. Within the Packages, you can find Pre-Built Components, Private Components and Functions.
All files inside Packages can be easily implemented inside your projects as a Dependency - Dependency - When you create a Project, you can select Components and functions from your Packages as Dependencies. If you edit a Component, the changes will apply to all the Projects which have that Component as Dependency. . You can select a Pre-Built Component, or clone to edit them, simply hovering over them, adding new Resources and your business rules. This will turn it into a Private Component.
If none of the Pre-Built Components fits you, you can also create a Private Component to connect with any endpoint online. Check how to create a Private Component here.
You can easily start a Project in the Packages list, selecting Components and Functions as a Dependency.