In the domain, move the "spotlight" as you wish. With a mouse button down, you can drag a zero (root) to a new location.
To make an additional zero, get it from the zero box at the upper left; to remove a zero, move it to the zero box. It is OK to put one zero on top of another.
Notice how when two lines in the domain cross at a right angle, their images do too, except at certain places. What are these places? (A function from a plane to a plane is conformal wherever it preserves angles.)