you need to place the games inside on this directory, under root of the drive:
Pick either of them (I recommend GAMEZ since all known Backup Managers use the GAMEZ directory)
under GAMEZ directory (or GAMES) you can place the backups there.
GAMEZ/BLUS31020-[Lost Planet 3]
Inside the certain specific game directory, the game files place there like the PS3_GAME and PS3_DISC.SFB (PS3_UPDATE directory is unnecessary and can be deleted safely at will)
Also to copy games from internal to external, choose the game that you want to copy and press triangle, and choose copy, it will nag you to copy from USBxxx (xxx is replaced by numbers, depends on how many usb storage device you have in your PS3) and chose OK.