Here are a set of handouts and questionnaires about emotions. It seems helpful to understand emotions through an evolutionary perspective - we have emotions, to a large extent, because they had (and have) survival value. We are the descendants of people with adaptive emotional systems that helped them stay alive and function well. Typically unwelcome feelings that seem maladapitve are due to emotions that are firing off inappropriately. As a rule of thumb, if an emotion is an appropriate reaction to a situation it can help us respond successfully. If the emotion is inappropriate then it's likely to be more useful to work to change the emotional response - through therapy or other approaches.
Emotions are like a ‘radar system' - this pair of Powerpoint slides, that I print out as a two-slides-to-a-page handout, introduces the idea of emotions as an evolutionarily adaptive system. I use the metaphor of emotions as a 'radar & rapid response system' - normalising emotions and conceptualising emotional problems as inappropriate levels of activation in a basically adaptive system.