(If you really want to explore the Mandelbrot Set, try xMandelbrot.)
To zoom in, drag on the picture with the left mouse button.
To zoom out, hold down shift key while dragging.
The Mandelbrot set is the black area. Zoom in along the boundry
to see incredible detail. You need to increase Maximum Iterations
as you zoom in.
As you zoom in, some areas that should be colored are black,
because the maximum number of iterations is too small. Increasing
the maximum iteratios might fill in some of the black area with color.
If the color looks too uniform, trying turning off the "Stretch
Palette" option and setting the palette to be less than the maximum
number of iterations. If the colors change too quickly, try
increasing the palette length.
If you zoom in too far, you will exceed the precision that is used
for real numbers on the computer, and you'll see blocks of color instead
of individually colored pixels.