How to improve my singing?

hi my name is malcolm and im 14 years old and im currently working on some songs for a upcoming demo tape i was wondering if anyone had any tips that could help strengthen my voice i am going through puberty so the highest i can sing is a href="http://www.youtube.com/watch?v=d2D-UYPgvVg" rel="nofollow"http://www.youtube.com/watch?v=d2D-UYPgv…/a china mcclain sing dynamite but even when i sing that song there are some restraints on my vocal chords. Does anyone have any techinques or methods or activites that i could do to improve and strenthen my singin voice