Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:6/8
K:G
['', 'A B2 G c2 A', 'g3 B2 B Bcd e3 efg dcB']  
X:1
L:1/8
M:6/8
K:G
 D |: GAG FED | E2 F G2 A | B2 G c2 A | B2 G c2 A | Bcd E2 E | ABG FED | EFG AFD | G3 |1 G2 D :|2 
 GBc |: d2 d def | g3 g3 | B2 B Bcd | e3 efg | dcB cde | d^cd D2 D | EFG AFD | G3 |1 GBc :|2 G3 ||  