Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:2/4
K:F
['F2 ED']  
X:1
L:1/8
M:2/4
K:F
 c2 cd | G3 c | AGFD | G4 | c2 GA | F2 ED | C2 c2 | G2 AG | F2 ED | GAGF | GFED | C4 |]  