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
['BE PE2', 'Beed egfe']  
X:1
L:1/8
M:4/4
K:G
 BE PE2 BEGB | AD PD2 FGAd | BE PE2 BGAF | GBAF E2 GA | BE PE2 BEGB | AD PD2 FGAd | BE PE2 BGAF | 
 GBAF E2 GA :| Beed egfe | defa afed | Beed efgb | agfa geed | Beed egfe | defg agfd | efga bagf | 
 egfd Pe2 dc :|  