MMORPG.com Flyff Correspondent Michael Hoyt writes this look at Flyff for beginners.
After you have registered for your GPotato account, click the download tab. Select the website you want to download the client from. Depending on what browser you use, click the link and run the file. Keep everything already written such as file names and folders that contain major information. After a while you will see a download status bar. Usually it will say that you have hours to wait. This is not a joke. FLYFF does take some files from the internet while downloading. Therefore it is not advised to download FLYFF on a wireless computer. Even on a high speed internet computer it is advised to leave the computer alone, do nothing on it while the game's client is downloading, and relax. Soon it will finish downloading and a message will pop up. Click the finish button and you're done downloading the client. Now pat yourself on the back and say "Well done".
Read A Beginner's Guide