well first, you have to format the drive you want the games to be on to WBFS
you can do this with the loader itself, or a WBFS GUI for the PC
(formatting will erase everything, but if you make partitions only that part will be formatted)
When you've done that theres 2 ways to add an iso
1) Use a WBFS GUI, simply click add iso and browse for it
2) With the loader: insert a disc then click + on the loader and it will rip the game to the USB device
you can do this with the loader itself, or a WBFS GUI for the PC
(formatting will erase everything, but if you make partitions only that part will be formatted)
When you've done that theres 2 ways to add an iso
1) Use a WBFS GUI, simply click add iso and browse for it
2) With the loader: insert a disc then click + on the loader and it will rip the game to the USB device