Mostly, by default whenever you publish something somewhere they automatically assume you have/want the copyright. But on many platforms you can choose to publish in the Public Domain or several Creative Commons licenses (CC-BY is what I would consider the only properly "Open Source" CC license).

As for the contest, it should be a new song / project. The details will be posted soon, but basically the idea is this:

1) We have a prize/commission (200k+ sats)

2) Artists propose what they would (and could) create for that prize/commission - along with proof of previous works (they don't create it yet)

3) People vote on the best idea / artist

4) Votes are tallied up, the best idea / artist gets paid 50% of the prize, they create what they promised to create, they get paid the other 50%

5) The newly created work is published in the nostr:nprofile1qyd8wumn8ghj7cn0wd68ytnvv43hgatjd9n8jtnwv46z7qg4waehxw309a5xjum59ehx7um5wghxcctwvsqzqr5g4trndr2lykpyx7pxqs4nlvazdgfx70v9wcvvddn99204h7s27tcduj Open Source Culture section and the public domain

Hope this makes sense :) If not, more details coming soon! Or just ask any further questions you might have 😉