Alex, there are several ways to get that data from your Windows computer to your iFly.  
1) Local Share:  If you have all your devices connected to the same WiFi network, on the Flight Plan you can touch More Options -> Share with Local Devices.  This will push a message through the network to other devices, and they should prompt you to accept the flight plan.  This method is problematic as many routers, firewalls, and/or devices block this type of data burst, so it's not super reliable on all networks.    
2) Cloud Share:  With our latest version you can enable an automatic sync of your data to our servers.  You can access this feature by touching Menu -> About -> My Account -> Sync.  You can upload from a device to our server, essentially backing it up.  Or you can download from any of your other backed-up devices.  
3) Manual: You can manually copy flight plans and other files from your windows computer to your iFly device.  The default location for your flight plans on your windows computer is C:\_iFlyGPS_Data\User\#FlightPlans.  Copy any files from here to your SD card \User\#FlightPlans folder
-Walter