hi - i'm 17 also!! coincidence. yeh well in terms of kissing, please believe me, it comes so naturally! there are NO rules, anything! just be sensible, don't pull your tongue out if they haven't! but if their mouth remains closed, put yours out lightly and prompt them to do it!
massage your tongues together, break this up with pulling their tongue with your lips, kiss their open lips, anything! if you are passionate about them, i swear you will be amazed with what you can do!
i happen to love kissing and have also been told i'm really good - whether its true or not, who knows, but i love doing it because you can make it up as you go along! good luck