There's an easy way and a hard way to publish music on iTunes. The easy way is to use an Apple-approved aggregator -- an expert that delivers your content to iTunes for a fee. Publishing your music to iTunes yourself without an aggregator is free but challenging. You need a U.S. Tax ID, a UPC for your album and a unique International Standard Recording Code for each track. In addition, the album must be available on a record label.
Publish With an Aggregator
It is impossible to publish your music on iTunes if it is not available through a label with at least 20 albums in its catalog unless you use an aggregator. Apple maintains a list of approved aggregators (link in Resources), which makes it easy to find one with pricing and features to match your needs. Expect to pay at least $40 to publish a single album. When you use an aggregator, Apple's business relationship is with the aggregator, not with you directly.
Publish Without an Aggregator
If you are ready to go with a U.S. Tax ID, a UPC for the album, ISRCs for each individual track and a record label, proceed to the iTunes Connect application page (link in Resources). Sign in to your Apple account and complete the application with the required information. According to Apple, you will receive an email response within four to six weeks. If your album is approved, the email includes a link for uploading your music to the iTunes Store. If your album is not approved, Apple requests additional information or identifies the changes required to publish your music on iTunes.