2. Click on the "view/edit" button for your album
3. Click on "Digital Track Price" (located under the "Pricing on CD Baby"
4. Fill inn "0" in the field with the price of the track.
5. Click "Save and continue" on the bottom of the page.
It may take 24 hours before your change is visible on your artist page. Then you can promote your artist page at CDBaby and let your fans know that they can download one (or more) track for free!
Here is and example of how the album page will look like when the first track is set as free: Look