You need two circles, one larger than the other, with different fill colors.
You can drag out an ellipse holding the Ctrl key to make it a circle. Note that the height and width have to be equal for it to be a circle.
Note the width of the larger circle, Let it be X
Let the width of the smaller circle be Y
Fit the canvas to the width of the larger circle.
Now, the position of the Left of larger circle is 0, and the right of it (Left+Width=0+width) is equal to its width.
Calculate position of left of smaller circle as follows:
Left [Smaller]=X/2 -Y/2
If you need to position text at the exact centre of the smaller circle, you’d do it like this:
Left of Text=Left of smaller circle+Width of Smaller circle/2 – Width of Text/2
Height of Text=Top of Smaller circle+Height of smaller circle/2 – Height of Text/2