Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:2/4
K:G
['DE GA', 'G3/2 d/ ed B/c/d ed dB/d/ g>e']  
X:1
L:1/8
M:2/4
K:G
|: F/ | GG/E/ DE | GA B2 | ed BG/B/ | AG EF | G/A/G/E/ DE | GA B^A/B/ | ed BG/B/ | AG G3/2 :: d/ | 
 ed B/c/d | ed dB/d/ | g>e dB | AG ED | G>E DE | GA B^A/B/ | ed BG/B/ | AG G3/2 :|  