Plz any suggestions for me?? I really need help and an answer quickly! :)?

Why don't you ask the choir/music teacher at your school to help you pick out a song? He/she will be able to find a song that will fit your voice and style, and could be willing to practice with you before the show. Also, if I may give a little personal advice, unless you have instrumental-only tracks of those songs, you won't want to sing them at your show, because the audience will hear Aly & AJ singing and not you. Try to find a piece with accompaniment that can be played on the piano instead, that way the focus will be on you!