In the course, go to Resources and click on the the "Add" popup menu, then click on the "Upload Files" link

Click the "Browse..." button to select your file. To choose more than one file to upload at a time, click the "Add Another File" link. After selecting your file(s), click the "Upload Files Now" button.
*Note: There is a size limit of 60MB per upload.

Your file(s) should then appear in Resources.

More information on the Resources tool is available in this manual