There are several ways to locate someone on social media using their selfie picture. One option is to use Google's reverse image search feature. This allows you to upload a photo and see if it appears anywhere else on the internet. Another option is to use a people search and verification website like Social Catfish or PimEyes, which can help you find lost connections and verify a person's online identity using images, email addresses, phone numbers, and online profiles.
You can also try searching for the person on social media platforms like Facebook, Instagram, and Twitter. On Instagram, you can use the search bar to look for the person's username. On Facebook, you can search for the person's name and then click on the Photos tab to see if any of their photos appear in the search results. If you have a mutual friend, you can also try clicking on their friend's tab to see if the person you're looking for is in their list of friends.