There are two ways to make library items.
You can create your course checksheet and add library items as you go, through the "Learn" step as covered in these articles:
Getting Started - Step 1 - How to make a Course
How do I add Theory Steps to a Course
Or you can add items - documents, videos, audio files, website links and more - directly into your library all at once, to later upload into your checksheet(s). You can upload the same library item as many times as you want into any checksheet.
Note: You can add items to your library at any time.
1. In your sidebar, click library.
2. Click new library item.
3. There are different file types you can upload. Do so by clicking the green create + button.
4. Follow the instructions in each one to upload your existing file.
5. At the end, mark who you want to see the item.
6. Create document to save.
Repeat the above steps to enter all of your library items.
This article covers how to upload library items into your checksheet(s): Getting Started - Step 3 - Upload Library Items to your Checksheet
To add library categories, see: How to Categorise Library Items.