Success does not equate happiness as it depends on the individual. You can be successful and if you are not at peace with yourself or do not really love yourself you can definitely be miserable. When you are contented and not puffed up or haughty with your success you can achieve happiness.
Failures is not necessarily bad. It just means that you have to try harder until you succeed. You can fail and still be happy once you do not consider yourself a loser.
Failure is a motivating force to make you continue trying until you succeed. Happiness lies in knowing who you are as a person and your relationship with your fellow man.