What to do 4 ring worm?

Anti fungal cream. Buy over the counter anti-fungal cream like Clotrimazole and apply it twice a day for 10-14 days. If it doesn't resolve or if it worsens see your doctor.
Make sure. Some other rashes may look like ringworm. If you're sure that's what it is, try otc antifungal products like lamisil, (terbinafine) lotrimin, etc. If it doesn't clear within 2 weeks, see a doctor.