A couple time lapses to watch:
Then, read The Artist's Color Guide to Watercolor, chapter 5. This starts a new section of the book, where they look at each color of the rainbow, starting with yellows. Read the chapter, then play around with some blending using as many yellows as you have. Then, using the various pictures in the book as inspiration, try a study of something where yellow is the primary color, or even something in a monotone, like the studies that the author included on page 50.
Finally, do a painting, either copying your artist, or something of your own design. Remember to stop by the group and show off your work; it's so inspiring to see what everyone does!