The top fabric is supposed to be the sky, the two at the bottom the sea.
I don't like the combination of the sky blue and the sea green.
Clouds can act as a nice division. Fortunately the challenge packet contains a lace motive.
This motive is perfect for clouds.
I cut the motive apart, used fray stop for the cut ends,
..and rearranged them, then sewed them on.
All about the "Message in a bottle challenge" can be found here.