There are two options for adding links in Cc.
Option 1: As soon as you click in the text area of a section card for your lesson plan, you can paste any link that you've copied and a link will automatically be created.
Option 2: Once you add text in Cc, highlight it, and click on the link button in the upper, left corner of the screen. From here you can add a link.
Note: There's no limit to the number of links you can add to your lessons in Cc!