With one dog, you might consider trying skijoring -- that's a sport that gets your dog experience pulling in harness, but you've got to be on the skis!
Another approach is to acquire a second dog, and then train them together to pull a sled. Two dogs can pull a sled with one musher easily on a packed snowy trail that's pretty flat. And you could enter the 3-dog class in races.
Also, find your nearest sled dog club and see if they plan to have any training sessions. Mushers are friendly folks and likely someone will be willing to give you points!
Here's an FAQ online with helpful info -- copy the URL and paste into into your Web browser:
Our WorkingDogWeb.com page on sled dogs and racing has links to much more info and books you can buy to learn more. Here's the URL:
If you'll trply back about where you live, I'll try to help you find the closest sled dog club.