Multiply the diameter by π(pi). You may want to do this yourself as I am not sure how many numbers of Pi your teacher wants you to use.
Using 3.14, the circumference is 314 (100*3.14).
Now we divide 314 into 6 equal segments by simply dividing by 6.
314/6=52.33 continually or 52 and 1/3.
From here, we have to assume that point A and point C have point B in between them. (You might want to tell whoever created this problem that such an assumption cannot be made usually unless more information is provided.) That means that we have two segments of distance that Harold walks.
52 and 1/3 multiplied by 2= 104 and 2/3
Answer: 104 and 2/3 meters walked by Harold.