Every emotion we experience has a certian trigger and a physical state - the first stage in moving intentionally on the emotional scale requires understanding what is the emotion you are currently experiencing.
You do that by using a little visualization.
For example - if you want to experience depression , you close your eyes and try to recall a situation where you were depressed.
When you get such a moment you, notice all the feeling and sensations you are experiencing, how does the image you brought up looks sounds and feels like.
Once you get a clear understandig you write down everything you experienced and mark as depression.
You continue doing the same visualization to all the emotions.
And the you just practice changing the different qualities of the image.
The most important emotion to understand is love, and then when you are down you visualize the image you have for love and poof, the bad feeling is gone. When you practice it often the movements get easier every time. I hope this was helpful , good luck