Hey Annie,
Thanks for reaching out. The ratings and sorting you are trying to implement are possible, but would unfortunately require many code customizations to implement 🙁
So to implement the features you describe, you would have to write that custom code or hire a professional developer to write the code for you. We have a list of great developers here → http://m.tri.be/18k1 (and have no affiliation with any of these folks–they’re simple some well-respected names in the community that we’ve compiled to share in situations like this one).
I’m sorry to disappoint about this not being a default feature!
Please let me know if there’s anything else I can help with.
Sincerely,
George