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
['G2 BG dGBG', 'g2 dg Bgdg']  
X:1
L:1/8
M:4/4
K:G
 G2 BG dGBG | AcBA dBcA | G2 BG dGBG | AcBA GBEF | G2 BG dGBG | AcBA dBcA | G2 BG dGBG | 
 AcBA GABd || g2 dg Bgdg | egfe afge | g2 dg Bgdg | egfa g2 g2 | g2 dg Bgdg | egfe afge | 
 g2 dg Bgdg | egfa gBEF ||  