Had Burns On Back And Shoulder. Can I Expose Skin To Sun? Apply Sunscreen?

-Hi. I am a girl of 15 years and 4 years ago I got third degree burns over almost the entire back, and over the shoulder . I had two large pots boiling over me. In one there were vegetables and the other was the meat. This is now four years ago, and I wonder one thing then. Since there are four years ago and it is almost summer, so I would like to go in a bikini on the beach. Is it legal to expose my skin to the sun, or do I bathe in the t-shirt? And the legs where the skin from the transplant, I leave to soak them and expose them to the sun, or they must be kept in the shade, too? I ve heard a lot different. Some say I can sunbathe and swim and that s okay, others say I should put on sunscreen, but still must bathe in the t-shirt to not expose the back for too much sun. please help me.