Finding a right co-founder is one of the most challenging tasks for a startup. If you want to find a marketer or a business developer they will want to see a proof that your business model works and it does bring some money. You are going to want to get traction first, to be in a better position. In addition to this, may need to think about social media coverage and a strong team .
As for the resources, there are a few social networks for entrepreneurs and several discussion forums that can be handy in your search. I can mention three of them that I worked with CofoundersLab, Founder2Be and PartnerUpList.
I have mixed feelings about CofoundersLab and Founder2Be even though these are one of the most popular social networks for entrepreneurs. You will need to creating a profile; after this you can start networking and messaging entrepreneurs matching your search criteria. Not everyone is looking for a co-founder though, some users are interested only in networking or finding a job for a startup.
PartnerUpList I had more success with PartnerUpList. This is a free message board for entrepreneurs and small businesses. This is not a social network but rather an online classifieds where visitors can submit their posts even without registration, which makes things easier. It covers a wide range of topics from real-estate, to import-export, online business and blockchain projects. I think because of its simplicity, it attracts a lot of entrepreneurs and tech folks interested in finding a business partner.
To answer your last question. If you serious about finding a business partner, you should offer your co-founder equity and profit sharing. Make sure that you have all paperwork done in advance in this case.