You start on a habitable planet and you have to use its resources to build many machines that will help you to conquer all the planets and make them suitable for human life.

Mine the resources with machines and then use the furnace to transform them into ingots or panels that you can use in the fabricator.
Then, in the fabricator, you'll be able to convert those ingots into circuit boards, engines, etc.

Then, build a rocket to travel through space and colonize all other three planets!