How do you become more outgoing or fun?

i've been quiet my whole life and im sick of itt. i have a best friend who i used to be super close with. We are still close but she is really silly and pretends to act almost stupid in front of like everyone. We are both friends with the same group of girls but she has recently become closer with them. Whenever i am with her she acts really y and sarcastic whenever i say anything. she thinks she is better than me and i am starting to believe it. I know i am jealous of her, but i do not know what to do to become less shy and so kids seek me out to hang. i told her the other day to stop acting like a smart alec but i dont know if she really took it seriously. i am kinda more of a serious person which i kind of hate because i like to have fun. Sometimes when i try to talk to people i run out of things to say or it turns out to be really boring. i am 13 and next year i am going to be in high school.i do not want to be known as "shy" there. i dont know what to do.