To be angry is definitely not wrong, but how you express your anger, with whom you express it, the reason for it and the degree of expression for it, when done in an inappropriate manner makes it wrong. How can you express your anger and still be appropriate then?
Suppression is one way of expressing anger; however, this is inappropriate and unhealthy because inward expression of anger may manifest outward as physical symptoms like headache, high blood pressure that can lead to more serious conditions like heart attack and stroke.
Rage on the other hand is also improper because other than the physical symptoms, it can also cause harm to other people.
What is appropriate is to express anger when you are no longer emotional, so that the words you will use will be constructive and will not leave permanent emotional scars.
Be very careful with whom you express your anger; sometimes avoiding confrontation ends up having the anger projected to someone else. This is not fair to that person, so if you are at the height of your anger, it may help to stay away from people and take a walk.
When the steam has settled down, talk directly to the person concerned. Be tactful with words, focus on the mistake done rather than the person, criticize but do not blame. Focus on one incident only and do not go back to past mistakes.
Choose the right place where to express your anger, it should be somewhere private where other people cannot hear the confrontation. Remember that the expression of anger calls for the appropriate degree, which means you cannot be very upset over something so petty; in fact it sometimes helps if you will just ignore it, unless it is done repeatedly and intentionally.
Lastly, remember that a sure sign of a personâ€™s maturity is seen in his ability to control his emotions and deal with it in an appropriate manner.