To Add modules to a course, please do the following steps:
1. Open your course then Click on the "Edit Course" link.
2. Click on the Modules link located at the left side of the page.
3. Search for the module you want to add.
4. Then Click the Add new Module button.
5. You can add more modules into your course. You can also arrange the modules my Dragging them and If your done Click the Update Modules button to save and update the modules you have added.