How do I add my songs?

In Catalog, the sidebar has an Add Songs group:

• Upload: drop an audio file or browse for one. You can also add a title without audio and add the audio later.
• Downloads: pick from the audio files in your Downloads folder (the last 30 days; click Show all for older ones).
• Import from URL: paste a DISCO playlist link (the playlist must allow downloads) or a Dropbox link to a single file. Dropbox folder links don't work.

To add another version of a song, open the song and add audio to it. You can mark one version as the main one.