My first horse show and i need help?

i'm going to do a walk/trot class for my first show. should i wear a hunter jacket? eventually i will use it again cuz i'm a jumper. do i have to wear a hair net? what color shirt do i wear underneath? what color should my jacket be? and is it ok to wear gray breeches? oh and can i wear my half chaps over my padock boots or just wear my rubber tall boots?