Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:4/4
K:G
['', 'GdBBA GABG', 'DAGAB G']  
X:1
L:1/8
M:4/4
K:G
 ge |: GdBBA GABG | D(3AAA BG Abde | GdBBA GABG |1 DAGAB D G2 ge :|2 DAGAG G G3 g |: Dfaea fe d2 | 
 D(3fga ea faea | Dfaea fedB |1 DAGAB G G3 g :|2 DAGAB G G4 ||  