Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
M:6/8
K:Bb
['uF Bcd dcd B3 uG2 uB ABc', 'uf fgf']  
X:1
L:1/8
M:6/8
K:Bb
 uF | Bcd dcd | B3 uG2 uB | ABc cAc | A3 uF2 uA | Bcd cdc | dfb bab | gfe dcd | B3 G2 :: uf | 
 fgf dBd | f3 uB2 uf | fgf edc | B3 uG2 uf | fgf edc | Bdf bab | gfe dcd | B3 G2 :|  