Not exactly easy, but works:
If you click on 'import' on AFF FT it gives you the recipe for importing from FM and its pretty much exactly what you need to do, but it took me a couple of goes.
You basically open up FM under the 'Flight Data' tab. This should list, over a number of pages, your flights.
For each page of Flight Data, you go to your browsers top menu (I use IE10) and 'save as' - this will save the web page. I remember you have to save it particularly has .html, not .hml Then, you use the AFF FT import pop up page and navigate to the saved web page files, and then 'upload' them one by one.
On importing, it will flag possible errors and it will stop the import if (from memory) you have airports not in the AFF FT list, or indeed airlines. (DJ Vs VA might cause problems). I had an obscure Alaskan airport in my FM data, and there is a facility to add new airports to AFF FT list, but it didn't work for me and Admin kindly added it in for me.
Good luck!