3. A frog starts from point $A(-6,3)$ and jumps to point $B(-2,5)$, then from point $B$ to point $C$ on the $y$-axis, continues from point $C$ to point $D$ on the $x$-axis, and finally returns from point $D$ to point $A$. When the total distance of the frog's four jumps is minimized, the positions of points $C$ and $D$ are represented in a Cartesian coordinate system (保留作图痕迹), the method is: 

(Note: "保留作图痕迹" translates to "保留作图痕迹" which means "retain the construction marks" in this context.)
3. As shown in Figure 5, the steps are as follows:
(1) Draw a Cartesian coordinate system, and points $A(-6,3)$, $B(-2,5)$;
(2) Draw the point $A'$, which is the reflection of point $A$ over the $x$-axis;
(3) Draw the point $B'$, which is the reflection of point $B$ over the $y$-axis;
(4) Connect $A' B'$ to intersect the $y$-axis at point $C$, and the $x$-axis at point $D$. Then, $C$ and $D$ are the points required.

Note: By the principle that "the shortest distance between two points is a straight line," the minimum perimeter of quadrilateral $A B C D$ is
$$
A B + A' B' = 2 \sqrt{5} + 8 \sqrt{2}.
$$