If you find yourself becoming intimidated by the concept of value relationships, try an exercise like the one below. I don't have a natural ability for color theory. So I've spent time playing with fabric trying to attain some skill with color. Working with a monochromatic palette makes it easier to understand.
For this project I chose a quilt block that had three colors. I replaced the colors with Grey Scale equivalents; the lightest color becomes white, the darkest color becomes black and the remaining color becomes grey. Now chose a color to work with and find three values in that color, light medium and dark. Make a few samples to see the results of your selection. Don't forget to play with the borders.