There are so many things, I don't know just quite where to start. Have you read the link to Anger on the Home Page of this website? Self love and self esteem, along with lack of forgiveness could be issues. Relationships - often with others, but more often with ourselves, can trigger anger and this can stem from emotional issues such as blame, guilt, judgements, frustration ... and more. I know that I had a huge issue with anger, which was all part of my grief process.
Anger is one of life's great challenges which touches all of us at some time in our life. If one continues to allow anger to be an issue in one's life, without doing something about it, then it can have severe consequences, including impaired health. Who wants to be angry all their lives? And remember basically we're doing it to ourselves.
Anger can become like a habit which is deeply embedded in the subconscious mind - it's the subconscious mind that we have to work with. There are a couple of tools that you can start with - perhaps the book "Switch On To Your Inner Strength" and maybe the meditation tapes (or CDs): PP9 - Letting Go Anger, PP13 - Inner Peace & Harmony and PP10 - Self Worth & Confidence. A suggested program is:
1. Buy "Piece of Mind" Pack - read the book and do the exercises. Keep practising getting to your "Peaceful Place" fast (this will be explained in the book).
2. Buy the tape (or CD) "A Peaceful Place No. 9 - Letting Go Anger". Do side 1 of this tape (or Track 1 on the CD) and then do side 2 every day (you will be doing side 2 of this tape whilst you are reading and doing the exercises from the "Piece of Mind" book) - my guess is that you would do this for about a month.
Note that I have not addressed relaxation - this will come automatically by using both the tapes mentioned plus the Piece of Mind Pack.
If you are able to attend a CALM Life Skills Seminar in your area it would also address the anger issues.