FlashCards has a whole suite of Online Tools designed to help you create your flash cards from your desktop computer. Just visit
http://www.flashcardstogo.com
Choose "Online Tools" from the navigation. If you do not have an account already, you must create one.
Here you can create your sets manually, even with an HTML Editor. You can also import from CSV, Quizlet, Flash Card Exchange, StudyStack, Pro Profs, FlashCardDB.com, and more.
Once your sets are created online, you download them to your device. Tap "Download" from the opening screen, then "My Online Sets". All of your sets created online or backed up from the app will be available for download.