Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:12/8
K:G
['', 'G2 B d2 g b2 g d2', "g2 b c'2 b a2 e e2"]  
X:1
L:1/8
M:12/8
K:G
 B |: G2 B d2 g b2 g d2 B | cBc agf gfe dBA | G2 B d2 g b2 g d2 B | cBc agf g6 :| 
 g2 b c'2 b a2 e e2 g | f2 a abg f2 d d3 | g2 b c'2 b a2 e e2 g | faf def g6 :|  