It is never advisable to use sunbeds or allow yourself to burn in the sun.  Being burned can increase the chances of getting melanoma in later years.   The thing to do now is realise the potential damage and start making changes.  Avoid sunbeds and don't lie in the sun unprotected.  Remember to use good quality high factor sunscreen, stay out of the sun when it is at its strongest and protect the delicate skin of children.