Construct a musical composition following the given alphabetical structure and incorporating the specified motif.
X:1
L:1/8
M:2/4
K:Bb
['f>g fe dB B2', 'dB ec']  
X:1
L:1/8
M:2/4
K:Bb
 f>g fe | dB B2 | GccB | AF F2 | f>g fe | dB B2 | G2 A>A | B4 :: dB ec | dB ec | Gc cB | AF F2 | 
 dB ec | dB ec | G2 A>A | B4 :|  