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
['AGF A2 B', 'g3 f2']  
X:1
L:1/8
M:6/8
K:D
 A | dfd B2 B | AGF A2 B | ded def | g3 f2 e | dfd B2 d | AGF A2 B | d2 g fge | d3 d2 :: A | 
 d2 g faf | gbg faf | d2 d faf | g3 f2 e | dfg aff | bgg agf | (edB) (BAB) | g3 f2 e :|  