You should avoid sunlight if you can.
Apply calamine lotion after keeping it in fridge for 15 mins on the skin area that's burnt, multiple times.
You can also apply some aloe vera gel if you have.
And apply physical base sunscreen everyday.
Next Steps
if the skin is still red or blistering please consult with a local doctor.
Health Tips
donot apply any active skincare agents while the skin barrier is damaged.