Construct a music composition that complies with the designated structure and theme.
X:1
L:1/8
M:6/8
K:Bb
['d2 f']  
X:1
L:1/8
M:6/8
K:Bb
 f | f2 ffge | d2 d d2 f | e2 cd=ef | c3 c2 f | B2 B e2 d | cde d2 f | fdBecA | B3 B z |]  