Hello, Tracy,
You have a couple of options to get from the Cabins at Fort Wilderness Resort to
Disney's Boardwalk. The simplest way and most direct route is to take a taxi, and Bell Services at your resort could make those arrangements for you.
If you'd prefer to use Disney transportation, it is very easy to get to Disney's Boardwalk from Epcot. There is a back gate at Epcot called the International Gateway located between the United Kingdom and France; you can exit from there and walk right to the Boardwalk (go to your left as you exit; going to your right takes you to Disney's Yacht and Beach Club Resort). Similarly, you can also take a boat from Disney's Hollywood Studios to the Boardwalk.
To return to your resort later at night through Disney transportation, you'll want to first return to a theme park. You may find it easiest to go to Disney's Boardwalk Inn and then catch a bus to the Magic Kingdom. A cast member can help you find the bus stop at the resort. From the Magic Kingdom, you can easily return to your resort by bus or boat.
To help you to visualize all of this, this
map of the Boardwalk may help you to see more of what I'm describing as you can use the controls to explore all the areas I spoke about.
Happy planning and please let us know if we can help again
-Kara