From the “My Courses” page, open the drop down menu by clicking the arrow on the “View” button next to the course you want to add new lessons to. Next, choose “Customize Course."
Type in the name or subject of your desired lesson such as "nervous system" in the search box beneath the "Available Lessons" title and click "Go."
Click "Add" beside each new lesson you would like to add to your course. The new lessons will now appear in the right-hand column under "Selected Lessons." You may rearrange lessons using the green up and down arrows next to each lesson name.
Repeat the process to add additional lessons. Once you have added all the courses you would like, click the "Finished" button to complete the process.