She just basicly wants to know how to find the circumfrence.
Im not sure if this is a question but I will tell you the formula for fidning the circumfrence of a circle :)
You multiply 2 by π which equals 3.14 then you multiply that by the radius which is half of the diameter, then square that number :)
The formula to find the circumference of a circle is C = 2πr.
π ≈ 3.14
r = radius.
Substitute for the values and then solve, and your answer will be the circumference of the circle!! Its as easy as that!