To restore a course:

1. Go to Administration > Front page settings > Restore (if you have front page permissions) or Administration > Course administration > Restore (if you have an empty course to restore into.)
2. Upload the backup file or choose a file in the course backup area or user private backup area and click Restore
3. Confirm - Check that everything is as required then click the Continue button
4. Destination - Choose whether the course should be restored as a new course or into an existing course then click the Continue button
5. Settings - Select activities, blocks, filters and possibly other items as required then click the Next button
6. Schema - Select/deselect specific items and amend the course name, short name and start date if necessary then click the Next button
7. Review - Check that everything is as required, using the Previous button if necessary, then click the 'Perform restore' button
8. Complete - Click the continue button

Here is a short video to help.