It's completely easy.
Each set of cabin loops has a bus stop. Two routes go through the cabin loops, one is direct to the Settlement Area for the marina, beach, Trail's End, Hoop De Doo and boat to MK and Contemporary/WL. The other makes stops along the way at the Meadows Recreation Area for the trading post, main pool and other activites, but then still goes on to the Settlement.
Either bus also goes to the Outpost, which takes you to the bus stop for the park buses.
Buses run all the time, probably every 10 minutes tops.
You will receive a map at check-in and the bus lines will be shown on the map. Take a few minutes to go over it with the CM at check in. He/she will explain which route to take to go where, and will circle them on the map for you. It used to be Purple was direct and Orange stopped at Meadows, but I think that's changed so I don't want to give any advice on that. Just ask at check-in and you'll be fine.
http://www.wdwinfo.com/resortmaps/fortwilderness.htm Here's the map. You'll see, it's pretty straightforward - follow the color lines and it makes sense.
Remember when you're staying at the Fort you don't have a food court so don't expect to just run out for breakfast. You can get lunch and dinner at Trail's to Go, Crockett's Tavern or the Meadows Snack Bar.
We love the Fort and would recommend it to anyone. Get grocery delivery, cook out on your deck, watch the fireworks and water parade from the beach, play shuffleboard, see Chip and Dale singalong and make s'mores. It's a wonderful, relaxed way to vacation at Disney World.
BUT if you're a GO GO GO family, you may get frustrated at the pace there and the fact that everything is not at your fingertips. For most of us, that's a plus, but for the people who don't do their research in advance, it's a rude awakening and very different from the typical resort stay at Disney World. Those are the people who complain about the buses.
I would recommend you ask for loop 2500, which is right next to the quiet pool and the laundry room. It's lovely there, surrounded by trees and you can sit and listen to the birds, watch the lizards and relax. I wish I was there right now
