Jeri, that post wasn't intended to be entirely serious, just a little dig at Steve Shaw.

Are you sure you really want to know? The short answer is that evolution simply means change and covers the idea that species that closely resemble each other (such as humans and chimpanzees or horses and donkeys) have a relatively recent common ancestor from which they have both diverged. As the resemblance decreases (such as humans and chimpanzees AND horses and donkeys), the further back the common ancestor must be.
Evolution by natural selection refers to Darwins theory on the driving force behind the change. Those organisms better adapted to their environment breed more successfully than those less well adapted. "Survival of the fittest".