Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
M:2/4
K:Bb
['F,F, CC CC C2 G,G, ||[M:3/4] B,G,', 'G,F,F, [M:2/4]', 'F,F, F,2 z2 ||[M:3/4] B,B,', 'B,B, G,2', 'G,G, F,4 F,F, ||[M:2/4] F,2 z2', 'F,F, F,F,']  
X:1
L:1/8
M:2/4
K:Bb
 F,F, | CC CC | C2 G,G, ||[M:3/4] B,G, B,2 B,G, ||[M:2/4] B,2 CG, ||[M:3/8] G,F,F, || 
[M:2/4] F,2 F,F, | F,2 z2 ||[M:3/4] B,B, B,B, B,B, | G,2 D,G, G,G, | F,4 F,F, ||[M:2/4] F,2 z2 | 
 F,F, F,F, | F,F, F,F, | F,2 z2 |]  