Develop a musical composition using the outlined alphabetical depiction of the structure and the provided theme.
X:1
L:1/8
M:6/8
K:D
['AFA dcB BAG FED', 'AFA dfa agf efg (f/']  
X:1
L:1/8
M:6/8
K:D
|: B | AFA dcB | BAG FED | FAD FED | CDE EFG | AFA dcB | BAG FED | (f/ a3/2)f gec | ded d2 :: B | 
 AFA dfa | agf efg | (f/ a3/2)g fed | cde e2 A | AFA dfa | agf efg | (f/ a3/2)f gec | ded d2 :|  