Go to the Sprint website at Sprint.com and log in to your account. If you don't have an account, click the "Sign Up" button and create a free "My Sprint" account.
Click the "Digital Lounge" option, then click the "Ringback Tones" link in the navigation menu on the left side of the page.
Search for new ringback tones. You can search by genre or use the search field to find a ringback tone by a specific artist. To preview a ringback tone, click on the song link.
Click the "Buy Ringback Tone" link to purchase the new tone. Review your purchase and accept the monthly subscription charge.
The ringback tone purchase and subscription fee are added to your cellphone bill.