Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:2/4
K:D
['d2 FA dB df e2 B/c/d ef', 'ge fd']  
X:1
L:1/8
M:2/4
K:D
|: d2 FA | dB df | e2 B/c/d | ef g2 | ab/a/ ge | fd AF | GB AG |1 FD D2 :|2 FD De |: f2- fd | 
 g2- ge | fd fa | gf e2 | ab/a/ ge | fd AF | GB AG |1 FD De :|2 FD D2 ||  