Different shades of the same color will make the rings have the "fading" look... you can play with the directions you wish them to go. Putting all of the darker pieces on the ends of the rows may even give you a secondary design :D:D:D
I would suggest starting out with some scrap fabric and practice the piecing first. It make take you a few attempts to get the curved piecing down :wink: You can even buy some cheaper muslin to practice with.
Using the printed interfacing will make it easier, as you have more leeway with the piecing.