Next time say, " I want my lawyer". You're young, but you can see how they did this can't you? They talked to you to get you to CONFESS. Never, ever telling police anything will it help you. There job is to ARREST you, not help you.
Do you think police tell the truth? Hell no! They are trained in to do two things, intimidate and lie. I have a friend who is just about 50, and thought being "honest" with the police was best. HE HAS NO RIGHTS FOR THE NEXT YEAR.
Do NOT ever argue with a cop, no matter how wrong they are. I have scar's to prove this point. Don't confess, keep that mouth shut. Below I have posted a web site that explains how you should act, WATCH THESE, THEY MAY BE ALL THE HELP YOU NEED. Although they seem a little silly, look who made them.
http://www.flexyourrights.org/index.php
And here a few movie clips:
http://www.flexyourrights.org/busted/movie_clips
"We are all aware of the contents of the Miranda warning. It is recited on police shows everyday and can be repeated verbatim by most Americans, though often without a thorough understanding of its significance. In short, the Miranda warning is an acknowledgement of the criminal suspect's right to take what is always the best course of action for any arrestee: say nothing until you've spoken with a lawyer.
Still, the Miranda warning is frequently misunderstood as encompassing all lawful detentions by police. It should be noted that Miranda does not apply under the following circumstances:
1 Questions asked at a crime scene
2 Any statements volunteered by the suspect at any time
3 Questioning of individuals for fact-finding purposes
4 Questioning during an investigatory stop"