Take into account that the general form of the equation of a circle is given by:
(x - h)² + (y - k)² = r²
where r is the radius of the circle, and the point (h,k) is the point of the center of the circle.
In the given graph, you can notice that the radius of the circle r = 2, and the center of the circle is (-3,3), then, you have h=-3 and k=3:
replace the values of h, k and r into the given formula:
(x - (-3))² + (y - 3)² = 2²
(x + 3)² + (y - 3)² = 4