Develop a musical composition using the outlined alphabetical depiction of the structure and the provided theme.
X:1
L:1/8
M:4/4
K:Bmin
['fBBg BBfB', 'A3 A dAcA dAde fgaf g3 g']  
X:1
L:1/8
M:4/4
K:Bmin
|: fBBg BBfB | fBdf e^gae | fBBg BBfB | Aa^ga eAce | fBBg BBfB | fBdf e^gaf | gBBg fBdf | 
 eBcd eAcA :: A3 A dAcA | dAde fgaf | g3 g gefg | fefg aecA | A3 A dAcA | dAde fgaf | g3 g gefg | 
 aecA d4 :|  