What Should I Do For Highlights?

Okk, so I finally convinced my mom to let me get highlights, but she said i can only get a few and they are going to be kinda on the bottom layer. my plan is to get shorter layers on top so they show better. but my problem is the coloring. i have dark curly hair. i want purple and blue and i have no idea if there is any way to make them show on my hair. should i get a light blue? and a Royal purple? PLEASE HELP!