David Medici has a good piece in the Sheboygan-Press on intelligent design. The one nuance I would add to his short piece is that while design theorists do compare chance and design explanations for certain features of the natural world, more than that they compare intelligent cause explanations with all of the leading undirected cause explanations. Undirected cause explanations may appeal to chance, to lawlike processes (e.g., natural selection), or to a combination of chance and lawlike processes.
And as Medici argues forcefully, design theorists seek to follow the evidence to the best explanation among these possibilites, much as scientists do in other fields.