The best way would be to get a realtor and get your home listed in the MLS. That'll make it instantly accessible to literally hundreds of real estate websites local and national.
If this is a For Sale By Owner situation, I know that fsbomadison.com has Columbus, WI listings. Go to that site and click on the Seller Information link at the top for info on how to list there. The problem with going it alone is that it's much more difficult to submit to multiple sites at once. Hope this helps, good luck!