Repeat question.....clothing help please...I really need help!?

Hey everyone! I ride Horses and I need some help I am going to a banquet on Saturday and I want to know if this is okay to wear......Im 13 years old... I was going to wear a Long shirt like a little above my knees leggings and ugg boots...is that kinda trampy? I want to look nice and I am not a tramp! Also I have another one on the 15 what can 1 wear to that alot of the same people will be their and I don't want to wear the same thing. me and My Mom are going to outlets on saturday. What should I get for that. Its not like a gown fancy but you cant wear like jeans. I am normal size for my age I am 5'3 and 105 lbs. I like name brand things..but It doesnt have to be..links would be greatly appriciated! Thanks everyone!!