Using the mid point formula
(x1 +x2)/2 , (y1 +y2)/2
F is the midpoint of A and B
F = (2+10)/2 , (4+6)/2 = 12/2 , 10,2 = 6,5
F should be (6,5)
Now you have A, F and B, use the midpoint formula to find the other coordinates:
D is the midpoint of A and F and is (4,4.5)
C is the midpoint of A and D and is (3,4.25)
E is the mid point of D and F and is (5,4.75)
H is the midpoint of F and B and is (8,5.5)
G is the midpoint of F and H and is (7, 5.25)
I is the midpoint of H and B and is (9,5.75)