Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/4
M:4/4
K:G
['c B']  
X:1
L:1/4
M:4/4
K:G
 B d c | c B B A | A B c B | B A G2 | z B d c | c B B A | A B c B | B A G2 | z D E F | G A B2 | 
 A B c B | A G A2 | z B d G | c B A2 | A B c B | B A G2 | z |]  