help?

so i am 16 years old, i am not sexually active exactly. but i am not a virgin and when i have sex i want to be safe so i want to go on birth control. my parents would never take but my friends are supportive and would take me to planned parenthood. (i have looked over different methods and i want to get the implant in my arm.) i was wondering if anyone could give me tips on what to expect going into planned parenthood and the side effects of this method.