You do not learn how to be happy. No book can tell you what to do. There is no step-by-step.
To be happy you decide to be happy. Then you monitor your thoughts and always move to happy thoughts when you find yourself thinking inaccurately. Only inaccurate thinking leads to states other than happiness.
How do you monitor your thoughts? Pay attention to how you feel. When you feel good you are thinking (perhaps not consciously) happy thoughts. The reverse is also true.
It does not matter what those thoughts were. Just switch to happy ones that leave you feeling good. Mind your moods and thoughts for 28 days straight and you will create the happiness habit.