They frequently make inappropriate comments to my coworkers even after they're asked to stop, one of them kissed my coworker on the lips out of nowhere, but she's afraid to do anything because she knows she'll have a target painted on her back. We don't have an HR department because our company is too small to require one.
There should be a labor rights sign in your break room or somewhere visible. See if they can call the number there. Failing that, check out this form maybe? https://www.eeoc.gov/filing-charge-discrimination