Open OneDrive settings (select the OneDrive cloud icon in your notification area, and then select the OneDrive Help & Settings icon  then Settings.)

1. Open OneDrive settings (select the OneDrive cloud icon in your notification area, and then select the OneDrive Help & Settings icon  then Settings.)

2. Go to the Sync and backup tab.

3. Select Manage backup.

To start backing up a folder, toggle any folder that says Not backed up, and then select Save changes.