You'll need three different colors from your "blocks" fabric for this block, so select three and designate them #1, #2, and #3.
You'll need:
Eight 5" squares of background fabric
Four 5" squares of fabric #1 (Grey)
Two 5" squares of fabric #2 (Floral)
Two 5" squares of fabric #3 (Zig Zag)
Four 5" squares of fabric #1 (Grey)
Two 5" squares of fabric #2 (Floral)
Two 5" squares of fabric #3 (Zig Zag)

Using the directions from this blog post, use the above fabrics to make 16 half square triangles. Arrange them as seen in this picture.
And sew the rows together, matching up corners, to get the finished block