@conradt nice to see you around :)
Curation basically means upvoting content. You curate too and receive curation rewards for it. There are also a lot of curation projects out there such as @ocd Groups of individuals that combine their Steem Power, resources, time and effort to curate content.
You don't have to give anything back to curators. Just as a member of Steem community think about it as investment in people. The more you invest in community, the more community gives you back.
There are lot of posts about curation out there. Here is just one example:
https://steemit.com/toolkit/@sndbox/earn-steem-by-upvoting-how-curation-rewards-work-on-steemit