Some people feel that when they are angry that the best way to deal with it is to express it, often loudly. What may be surprising to many, that is not only is that not the most effective way to communicate with others, it is also not the most effective way to deal with anger.
So, what is effective? First, it is okay to be angry. There are no bad emotions. Some are less comfortable than others, but none are bad. Be aware of your anger. Be aware of what triggered it. Be aware of what you are needing to communicate or to ask for.
Second, calm yourself. Take a few deep breaths. Separate yourself from what is triggering you. (Time outs are not just for children!) Once you have done so, you may be able to better answer why you are angry and what you are needing.
Third, approach the person that you need to communicate all that you now know. Ask if they are ready as well to have a conversation. Gently, slowly, carefully state what is upsetting you and what you are needing. Be prepared to hear what they need as well. Be prepared to hear things that you may not be comfortable hearing. Be open. If you need to again calm yourself or separate, please do so. Be prepared to compromise.
By doing this, you may be surprised that you actually feel calmer and that you are getting your needs met. Which will also make you much happier!