Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:2/2
K:G
['F |]: DG', 'ABcA dedB', 'dggf g2 fg abag', 'FA GBAG FDDA BG G2 AF F2']  
X:1
L:1/8
M:2/2
K:G
 F |]: DG G2 ABcA | dedB cAAc | B2 GB A2 FA | GBAG FGEF | DG G2 ABcA | dedB cAAe | f3 d edcA |1 
 GBAF G2 GF :|2 GBAF G2 Bc |] dggf g2 fg | abag fddc | B2 GB A2 FA | GBAG FDDB | dggf g2 fg | 
 abag fdde | f3 d edcA | GBAF G2 Bc || dggf g2 fg | abag fddc | B2 GB A2 FA | GBAG FDDA | 
 BG G2 AF F2 | dB B2 cAAe | f3 d edcA | GBAF G2 GF |]  