Try Linkedin, Meetup, Eventbrite and you might find someone who needs a mentor, make your intentions clear so they know what you are offering.
Once you have students who need help you might test them by giving assignments and see how enthusiastic they are and how much effort they are putting into it, then you can either accept them as a mentee or let them know that they need to up their game to need your guidance. You can't help those who don't want to help themselves.