You pretty much need to start the colony yourself then they take over. The problem is that if they have multiple choices they tend to concentrate on the highest demand. I had colonies set up on Venus, Luna, Mars and Ganymede nearly simultaneously. The civillian shipping concentrated on Luna first, when it was at 25 million and I set it to "stable" then they switched to Mars, when it got set to stable they switched to Venus. That doesn't mean they ignore completely the others but the colonization of Venus cost a lot of people their lives as they dumped a lot of people there and seriously stressed the infrastructure. Something similar is happening with Ganymede where I think they could be shipping a load of infrastructure there once a month to meet their demand...instead they are essentially ignoring it because the demand at venus is so high.
I got really bad survey luck...of the planets and moons basically only Venus has resources and they are of the 35million, 0.1 availablity sort. The only other places with resources are Mars (one material), and one of the rubble moons of saturn. Outside of those I have only asteroids and comets. Thankfully two CMC started up (one on a comet the other on an asteroid out in the Oort cloud) as I have exhausted my Durium and Neutronium which basically cripples your growth. It took till the CMC started up on the comet that I noticed the button for "buy" the minearls.
As I put into the suggestion thead the logic for dealinig with demand needs a bit of work
But you need a colony ship and a freighters to start the process off, very quickly the civillians will take over. They have now 3 firms, the older two have probably 35 ships between them ranging from passenger liners to 60K colony ships and freighters. I have to admit I find them very useful for moving stuff around, and they are making serious money so far as I can tell given the strong increases in their share prices.