Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:2/4
K:C
['d2 dd BG Bd', 'G4 B2 BB G2 BB c2 cc']  
X:1
L:1/8
M:2/4
K:C
 d2 dd | BG Bd | dG Bd | dc AF | d2 dd | BG Bd | dc AF | G4 :| B2 BB | G2 BB | c2 cc | AF F2 | 
 d2 dd | BG Bd | dc AF | G4 :|  