How do you grow long nails ?

Ok school is starting in September,and I want to go to school with nice nails. The reason for this is because,this girl is always teasing people for their insecurities. Can anybody tell me how to grow long nails? I also heard 'Sally Hansen Nail Harderner' works,and what do you do if you want your nails to grow nice and straight? - thanks for answers xoxo Gloria