Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:6/8
K:Gmin
['z z', 'z z']  
X:1
L:1/8
M:6/8
K:Gmin
 d | (dc)B (BA)G | (DC)D z z G | (AB)c (BA)G | d3 z z d | (e/f/)gf (e/d/c)B | 
 (FE)F z z (c/4d/4e/) | (dc)B (cF)A | B3- B2 :: B | f2 F (BA)G | (cB)A z z d | (ed)e (cB)c | 
 A3 z z g | (gf)g (ed)e | (c=B)c- c2 (c/4d/4e/) | (dc)B (BA)G | G3 z z :|  