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:G
['D GFG B2', 'g2 d B2']  
X:1
L:1/8
M:6/8
K:G
 D | GFG B2 G | c2 A F2 D | GFG B2 c | d2 g B2 c | dge =f2 d | cAG FGA | d^cd =cAF | G3 G2 :| d | 
 g2 d B2 G | c2 A F2 D | g2 d B2 c | d2 e =f2 e | dge f2 d | cAG FGA | d^cd =cAF | G3 G2 :|  