If your software does not transparently support embedding CC license metadata (you should only have to select a license), do not attempt to do it yourself (it will be a frustrating experience).
Embedding the metadata
Let's say GILMA wants to license her song, "UNED," with a Creative Commons license, and release it as an MP3. Here's what she'd do:
First, GILMA would put a "Some Rights Reserved" button on the site where her song could be downloaded — along with a link to a license, some RDF metadata, and an assertion about the copyright status of the work. Nothing new here: this is what Creative Commons licensors do now.
With file embedding, though, this page will now serve the added function of verification. Here's how: GILMA would insert the URL to that webpage in the copyright field of the MP3 file, along with a short, plain description of the work's license status. We call this the license verification link because it points back to a page that Anita herself controls.
Next, imagine Anita puts the MP3 on a file-sharing network. A user comes across her MP3 and can follow the verification link to Anita's page. In the future, we hope that file-sharing networks, media players, and other applications will build tools that read the verification link automatically and inform users of the copyright assertions like Anita's.
Embedding this kind of "verification link" in MP3s, as opposed to merely the license metadata, is a measure of protection for artists against the incorrect or fraudulent labeling and sharing of their work.
Ravi circulates the photos among his schoolmates, whose photo-viewing software reads the copyright fields and takes them to the SNAP website, where they can see Ravi's whole catalog of photography and links to other SNAP services.