Not sure if you mean from the airport, or from within WDW, so I'll give you both options.
From the airport, you will have to book a towncar service, a taxi, or Mears transportation. Disney's Magical Express does not service Shades of Green.
If you mean from within WDW, you will need to take Disney transport to the Polynesian, then go out the front door of the Polynesian and ask a Cast Member which walkway goes to Shades of Green. (There are so many winding walkways, that it's confusing).
Then use the crosswalk to cross the street and walk the pathway to Shades of Green. You might encounter a golf cart that will take you up to the front entrance, please tip him.
Shades of Green does provide bus service from the TTC, Animal Kingdom, and the Studios, BUT I think they actually check resort IDs. So if you are going there just to purchase tickets or visit and are not a SOG guest, you won't be able to use their bus.
Carol