Try your nearest public employment agency.
Browse Craigslist ads.
You can also trying finding freelance work on Upwork, but it usually takes a while for newbies to get clients and good reviews. You may not even be accepted onto the website due to too many other UI designers. There are online articles you can read about how to maximize your chances of being accepted. Basically you need to specialize in something more specific than UI design or web design.