I only ralized that the skin was soppsoe to slide over the head of your penis last year and I am now 18. My forskin is very tight and hurts a little when hauling it over. When it gets over my head and down a little it is very red and has a even darker red at the bottom or the head, almost purple, I play hockey so everyone showers together and I noticed that other heads are mostly white. Also on my penis there is a little smell always from it. If there is anyhting I can take or do please let me know thanks

Sounds like you may have phimosis.

Caring for the uncircumcised penis (http://www.cirp.org/library/hygiene/camille1/)

This site will tell you about the phimosis and the care and hygiene you need to do. If it is really affecting you and is painful and stays red/purple/painful, you will need to see a doctor, they can probably give you some type of treatment or discuss circumcision with you.