how can i express my anger?!

Music helps a ton. Art in general! When you're angry or immersed in any sort of strong emotions that helps to get it out and you get a nice product from it.

Sports are the same way too- a lot of that anger can be burned off in energy- you'll be WAY TOO tired to be violent towards your friends.

This is gonna sound funny but talking to yourself in front of a mirror helps too- if you don't want anyone to hear you blast some loud music and yell all you want.

After you do something like that you stop and think about what you can tell those who are making you upset- you sleep on it and THEN you go talk to your friends. And if during the conversation it starts getting a little heated again you can tell them that maybe you should talk about that later because it's frustrating you and that you need to think. :)

I'm a VERY angry person- and this all helps me (except the sports, that actually helps a super angry friend of mine)

A diary.
Art.
Filming a rant.
Short stories.
Writing poems.
Photography usually helps people calm down and focus on other things.

take a sht in the dumpster. it makes everything better.

hit people with your fists