First, you have to understand the reasons for your anger and understand its causes. Some of the things you can do to control your anger include taking in a deep breath, drinking a glass of water, take a walk, meditate and try not to talk.
Having been through anger management class myself, I'll share this one with you: Instruct your friends & family to have digital video cameras at the ready & to record a 30--60 sec clip of you at full tantrum. Then ... you watch yourself. When you see how f'n silly you look, you'll never do it again. Good luck!!
I agree with MungBean, because it's first important to understand why your angry and what has caused such emotion. Once you understand why, then fixing it, or rather controlling it becomes a lot easier. You can try things like picturing something pleasant, removing yourself from the situation which is angering you, or simply taking a time out. There are many ways of controlling anger, the difficult part is learning how....and in my experience, it takes a lot of practice. Hope this helps :)
So pick "one" thing today, just "one"thing at the moment you feel it making you angry "you" decide which "one" for today, you let that "one" thing go, which ever "you" decided it's not worth me getting angry for and let it go.... tomorrow, do it again, just "one" thing again, just practice and believe me, do this and befor you know it, it will become natural to you. You will let go of maybe two or three in a day without even realizing it, "but", just "one" today! Again tomorrow!