Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:3/4
K:Emin
['B2 B2', 'e2 gf eB GB A2 Bc B2']  
X:1
L:1/8
M:3/4
K:Emin
|: e2 ed eg | B2 B2 AG | A2 (3BAG Ad | AG E2 z2 | z2 E2 GA | dA (3GAB A2 | GA B2 B2 | ge de e2 :: 
 gf eB GB | A2 Bc B2 | f2 dB A^G | =GA G2 z2 | z2 G2 AG | ^GA Bd f2 | B2 cB A2 | BG Be fg :|  