Having stayed at Fort Wildnerness several times, I can say that their interior bus system is very confusing. The HDDR is towards the back of FW, by the boat dock. Coming from another resort, I would suggest you take a bus to the Magic Kingdom and then take the boat from MK to FW. Once you get off the boat at FW, it is just a few minutes walk to the HDDR....you won't be able to miss it. That being said, I would suggest giving yourself about an hour worth of transportation time to get from Saratoga to FW.
Does that make sense? Any other questions?