The philosophy behind creating 3D models is similar to that used when working with clay. Basically, you start with a simple figure like a sphere and then use different tools to give it shape until obtaining your final result.
When using Sculptris, you can work from a flat surface or a sphere, using various sculpting brushes that make it easy to get the look you want. And, the mirror mode option allows you to create all kinds of symmetrical beings and creatures.
It's also possible to give color to your creation with different textures - you can even use images located on your hard drive, or mix between several effects just like you were using a 2D graphic design program.
Sculptris is a great 3D design program that also allows you to import and export your work in .obj format or Zbrush, another program created by the same studio.