@Jessica2014 I've ever used a co-host or been one, so I really don't know anything about it, but my understanding is that Airbnb used to provide this service, of having a list of local co-hosts that hosts could access, but doesn't anymore. That's why Helen probably suggested that you look for a local hosting Facebook group.
Just make sure that you have a solid written contract with your co-host, so there aren't any misunderstandings. And I would advise you to keep the listing under your account, rather than the co-host's, as reviews and ratings stay with the account of the listing administrator, not the listing itself. So if you found you weren't pleased with the co-host, it could be a pain to get the listing out of their name, and if there were good ratings and reviews, you'd loose all those if the listing was under the co-host's profile.
I've read several host posts here where the home-owner was dealing with just such an issue.