Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:2/2
K:D
['F3 E', 'D2 Addc d4 cdef']  
X:1
L:1/8
M:2/2
K:D
|: F3 E D F3 | G2 FG EFGE | F3 E DFAd | cAGE EDDE | F3 E D F3 | G2 FG EFGE | F3 E DFAd | 
 cAGE ED D2 :: Addc d4 | cdef gecd | Addc d3 B | cAGE ED D2 | Addc d4 | cdef gfge | f3 d efed | 
 cAGE ED D2 :|  