Mandelbulber is a fractal program with a difference. It moves beyond the usual abstract 2D images to produce amazing 3D fractals, with complex shading, ray-tracing, full lighting control, high resolution support (you can create images larger than 16,000 x 16,000 pixels), even the ability to create custom animations where the camera flies around and into your chosen view.
All this configurability does make for a complex interface, with more than 200 settings and controls spread across multiple tabs. But don't let that put you off: most of the options can be ignored, at least initially, and you can create some great images with very little effort.
Just clicking "Render" gets the process started, with Mandelbulber using its default settings to produce your first fractal. Click the View tab and you're able to manipulate this in 3D space: the left-hand buttons rotate the fractal; the right-hand buttons move your viewpoint; "Forward" zooms in; "Back" zooms out, and "Reset view" returns to the starting point.
Click the "Fractal" tab and choose a new "Fractal formula type" to produce different images. "Polynomic power 2", "FoldingIntPower2", "Smooth Mandelbox" and "Tglad's formula" are great places to start, while "Generalized Mandelbox Fold" manages to create Borg cube-type designs entirely mathematically. (Changing fractal type doesn't alter your view settings, so if you don't see the new fractal after it's been generated, click View > Reset view.)
As you zoom into these images, so you might want them to become more detailed. Click the Engine tab and try increasing the "Detail level" and "Max iterations".
The "Image" tab is useful, too. Here you can increase the image resolution, tweak brightness and contrast, as well as save your fractal as a JPG or PNG for sharing with others later.
And finally, if you're working on a really interesting fractal but have run out of time, click "Save Settings" to save the current Mandelbulber configuration, and "Load Settings" next time to restore it.
Mandelbulber is a hugely powerful fractal generator with an astonishing number of powerful features. This makes for an intimidating interface, but fortunately you don't need to understand its low-level technicalities to create some amazing images, and there is documentation to help you go further.