Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:2/4
K:D
['f>gfd (fa) a2', '(Tf2 e)d BdAd', 'f>gfd (fa) a2']  
X:1
L:1/8
M:2/4
K:D
 f>gfd | (fa) a2 | d'aba | d'aba | f>gfd | (fa) a2 | ad'af | dd d2 :: (Tf2 e)d | BdAd | edef | 
 BBB z | (Tf2 e)d | BdAd | faef | dd d2 :: f>gfd | (fa) a2 | d'a ba | d'>aba | f>gfd | (fa) a2 | 
 bd'af | dd d2 :|  