You can first use the mid-point formula to find the center of the circle:
midpoint formula says:
(x coordinate of center of circle)
and you do the same for your k (y coordinate) with the y coordinates of the given points.
So for your circle:
So the coordinate of the center of your circle are:
(h,k) or (-1,2)
Using that, see if you can figure out the standard form equation for the circle.