Question

my friend could not get selected to represent the school at the group annual dance competition she become rude with all how l could help her ressolve this issue

Answer 1

He/She is very angry because  he/she wasn't able to participate in the competition. Your friend  is very sad as he/she alone is not able to represent the school at the group annual dance competition.He /She is feeling inferior to her/his fellow participants and is angry with the dance teachers as they have not given chance to her.
         You should advise him / her not to feel sad. You should advise him/her to practice more dance steps so that he/she could get a chance next time.
You can also recommend him/her to  go to an expert dance teacher and learn more dance steps.