Whom to I envy and what do I lie about?

I constantly find myself on social networking sites looking at other girls and comparing myself to them. When I do this I grow jealous or envious of them for having the perfect hair, the great teeth and also wear the right clothes. I get down on myself because I put forth all my energy on wanting to be like them when I am clearly meant to be different. I am thankful for what I have and I am blessed to be given my wonderful family and friends so I try not to get caught up in wanting things that other people have. But what I lie about are silly things like when people ask my grades in a class or if I have gotten into a college or what my test scores are. I will lie and say I don't remember or I haven't heard back yet because I feel self conscience about this and feel that my scores will not be good enough. I have a feel of being a failure so I lie and tell people that I have completed something when I actually forgotten just to save myself from admitting to forgetting and having to let people down.