Anger - How to teach a child appropriate ways to express anger

[Earlybird]

Last night my dd hit me (not hard). She was angry because I wouldn't let her have a biscuit because she hadn't eaten her tea. When she hit me, I quickly got her out of her chair, and put her in her room for a time out. I said to her sternly "you don't hit mummy", and closed the door. When I went to get her 5 minutes later, I said it again. BTW, she is 3.5.

The whole episode got me thinking about how to teach her to express her anger in an appropriate way. Both my parents were screamers and smackers, with the silent "freeze out" treatment as a secondary method. That is NOT how I want to be with dd. I have problems expressing my anger even now, as I tend to view it as a destructive emotion, rather than a healthy one. I hope I can somehow teach dd that anger is a natural emotion that happens to everyone. But how to express it appropriately? Any suggestions would be appreciated.

I tell dd that she can be angry but that she doesn't have the right to make other people unhappy by being angry. She can go to her room and shout, but she can't hit people or shout down stairs. She goes upstairs and has a melt down and then tends to get over it. Mind you, she is older at 7, but we have been doing this for a while