You don't sound like the type of parent who would push your son into something... and that's really great. Too often, parents of kids with special abilities push their children in the direction that they think is best even though they have little or no interest let alone understanding of whatever the special ability of the child is.

1)
Ask him what he would like to do.

Go to the local library, community center and government office. Grab a ton of flyers, brochures, etc for artistic events and activities in your area. Let him pick at least 1 thing every weekend to go to. Simply by attending these types of things and getting him "into it" is pretty easy. All you really have to do is show up and show an interest in what he's doing.

2)
On top of that, give your son a special "art allowance" that he can use only on art related items. He should still have the standard slush fund for candy and whatnot, but if there's a "paint brush" fund that he looks forward to spending, this will go a long way too.

3)
Seek out local artists and ask if your Son can spend an afternoon or day with them. Our communities are filled with local sculptors, illustrators, painters, etc. Every art community that I have ever been involved with is always very open to this sort of mentoring.

4)
Encourage your son to show his work to others. It's easy for an artist (especially young ones) to become recluse and not display their work for feedback. Involve your son in local shows, competitions, etc. It won't all be rosy, but helping your son to realize the good with the bad is important. I'm not saying enter the artwork of your Son in advanced competitions... rather simply allow your son to receive honest and forthright feedback.

Best of luck!!!!

I would definitley seek the wisdom of a professional. Through your local
college, art classes, give the child all the tools you are able to and make it
fun for him. Do not make it demanding or he will rebel towards it.

I realize there are plenty of answers already, but I feel I can add some more to the discussion. If you are lucky enough to live in a community where there is a community of artists there may be an art league where your child can take classes. Also worth looking into are classes that are available for children and beginners at colleges and museums. Prior to applying to any one of these classes you should show examples of your child's work to someone to see what would be the best class for them. As your child progresses you will receive advice from teachers on where to take classes to further your child's education.

In regards to computer applications, it is good that your child has the initiative and drive to learn new software. Self study is how many people learn. Luckily there are a number of resources available to learn software online.
Starting with sketchup and other freeware like blender is a excellent path to take. There is community support for these programs and plenty of resources to learn the software. On Mahalo I started a webpage for SketchUp with links to tutorials. Eventually I hope to do the same for other applications.

As your child progresses and becomes more proficient, you may want to look into other online sites for computer art and applications such as lynda.com, thegnomonworkshop.com, and pixelcorps.tv.

Obviously, don't push him to the point he doesn't want to do it anymore. I say, keep it simple. Enroll him in some art classes, at the local art museum or something like that. At age 6, you should let him live his childhood. If he is as good as he sounds, everything will come together, you can start entering him in contests, shows etc. Most importantly, let him draw what he wants, just give him the supplies and the opportunities. Try not to go too fast with this.

If your assessment is accurate that your son is a child prodigy then expect rapid understanding and comprehension.

Ideas and dreams are important to a prodigy. They are excited about their vision of the world. Stand aside and let them create, it is what they do best. Help by letting your son know you support him and have confidence in his ability.

Most prodigy rapidly out perform their peers in school and college. Rapidly outpace their peers. Often they are bored because the system is design for medium level intelligence.

I think interest in their projects are important. Prodigies are very good at self-learning. They can pickup a math book and complete in a few days.

I think culture and travel could be helpful to inspire his imagination. It he could see and experience some of the master's work, it may inspire him. However, don't downplay sheer creativity. They are genius for this wonderment and ability to create where no else has thought.

Your son is six years old. What does a six year do? They create images of the world around them. Ok? Buy him a huge set of color pencils and pad of art paper. Let him create. He can work with colors and forms. The color pencils will help him sort through color theory. His work will bring attention.

I'm no expert, but I definitely agree that the important thing is to give him lots of opportunities to create art and expand his horizons.

One thing that springs to mind is to get him into some high-quality art class or program, possibly at your local art association. That would expose him to creative people who could help him develop good foundations for him to build on with his creativity. Or maybe a summer art day camp at a nearby university. Etcetera.

And definitely provide opportunities and supplies for him to keep creating his art.