I have heard it said that anger is a 'secondary' emotion. The primary emotion that it stems from being 'pain'.
I've used that concept to assess my own anger towards different situations and I have found that to be true for me.
Regardless, it's good to recognize what aspects of your life are troubling you and to start working through them by any means possible. Identifying them and writing them down is an excellent first step! I know the simple act of writing down what I am feeling always lifts a great deal of the burden from my soul.