You can add multiple blocks of formatted text content to your lessons.
Click your course name on the My Courses screen to view its Curriculum and Content screen.
Then find and click the lesson you'd like to add text content to. This will take you to the Lesson's Edit Content screen.
If the lesson is empty meaning it doesn't already have content you'll see a message and button like shown in the screenshot below.
Click the + Insert Content button and choose the Text option.
This will insert a rich text editor control.
Enter your text in the editor, format as desired, then click the Add Text button to save.
If your lesson already has text or other types of content you can hover over any piece of existing content to reveal the [+] button.
Clicking the [+] button opens the same insert content menu as shown above. This lets you to insert content between existing content.