Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
M:4/4
K:D
['f2 B2']  
X:1
L:1/8
M:4/4
K:D
 AB |"D" d2 f2 e2 f2 | defd edBA | d2 f2 e2 f2 |"G" g2 B2 B2 AB |"D" d2 f2 e2 f2 |"D" defd edBA | 
"G" BABc d2 BA |"A" F2 A2 A2 z2 ::"Bm" f2 B2 f2 B2 | fggg fe d2 |"Bm" f2 B2 f2 B2 |"A" edcd e4 | 
"Bm" f2 B2 f2 B2 | fggg fe d2 |"G" BABc d2 BA |"A" F2 A2 A2 z2 :|  