FD data is the NWS winds aloft forecast for Pilots. A good source for this file is located at:
http://www.awc-kc.noaa.gov/awc/awc-fd.html
To import the data from these files, go to that website, save the data into a plain text file in a folder where you will be able to find it then:
On the Main Screen, click [File/Open]. An open file dialog box appears. Select the file where you saved this data and the screen above opens.
Simply highlight the Name of the station you wish to import and click OK. NOTICE, above I've highlighted several lines. The only important thing here is to make sure your highlighting STARTS with the station you wish to import. In the case above, it's DEN (Denver). The program reads the selected text, strips out anything after DEN and uses that to "Find" those winds during the import routine. So don't go blind trying to select the three character station name, just be sure to start highlighting at the beginning of the Station you are interested in.
A reminder here. These winds do not exceed 39,000 feet. There used to be another file available with winds to 54,000 feet but I can't seem to find it anywhere. Anyway, if you are flying to altitudes significantly above this level you will need to find some source of winds for the Stratosphere so you can add them to this low level stuff.
Be careful when downloading this data. It generally comes in several forecast groups. One for the immediate future, another for 6 to 12 hours in the future and more further into the future. Be sure to download the prediction that most closely matches your launch time.