Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:3/4
K:G
['G>A B2 d>B c/B/A/G/ E>F', 'FE D>E GD', '']  
X:1
L:1/8
M:3/4
K:G
|: G>A | B2 d>B c/B/A/G/ | E>F G>G FE || D>E GD dB | A4 d>c | B2 d>B c/B/A/G/ | E>F G>G FE | 
 D>E GD BA | G4 :: A>G ||  