Hello Chris,
You don’t need any other software other than WD to create the 5 day forecast image.
You first need to start downloading a forecast from NOAA as noted here:
http://discourse.weather-watch.com/t/9168
http://discourse.weather-watch.com/t/23636
Once you have started downloading that then simply click on the Conditions Icon on your WD Desktop which should open the 5day forecast image and use the controls from there to start uploading it.
Note you have to be in the US for NOAA forecast downloads, not sure of your location as it isn’t in your profile, which we recommend adding as well as your station type…
-Bob