OpenBazaar is whole new way to buy and sell goods and services online. It's not a traditional website like Amazon or Ebay that works with search engines like Google, but a separate network of users connecting directly to one another. There are search engines within the application that help users to discover items within the network.
Since OpenBazaar is not a website, sharing your listings on social media is a little different right now, though we are working on ways to make this web-accessible.
For now, you can share your store and items using the ob:// link in the address bar along with something like a product image or screengrab. Users will need to have or download OpenBazaar to make a purchase so your best bet is to promote your listings in places where people are more likely to have OpenBazaar, like on the weekly recurring Shameless Self Promotion thread in Reddit, new every Friday!