Determine the copyright owner of the musical work you intend to use for your advertisement. Do this by searching the record company or music publisher. ASCAP and BMI are the largest music rights administrators, but you can check many others, such as the Music Publisher's Association and the U.S. Copyright Office.
Contact the publisher or copyright owner and request permission to use the work. Be specific and explain your intentions in detail. Outline how the work will be used. Draft a permission letter to send to the copyright owner, or contact the owner by telephone to explain your project.
Purchase the proper music rights license for a specified or negotiated fee. Although there are royalty-free sounds available for public use, most other pieces of music require the user to pay an organization, publisher or even the work's creator directly.