Have you not tried the using windows explorer, open one instance of explorer as essexboy showed in his post. Open a second explorer window, navigate to where the file is that you want to upload, drag the file from that window into the other explorer window (the empty right half of it).
CuteFTP is free or was when I used it. But honestly the explorer way is easiest as it doesn't ask any questions, doesn't require setting up to upload. The whole issue is that it is an anonymous proxy so you shouldn't need to enter any details other than inputting the ftp address. However, you would still have to know a little about FTP programs to use it.