Just...take a guess, dude.
It's not like you'll brick your wii by having the wrong file structure on your SD card. If things don't work, you can just try again.
It's like pepxl says: if you can't figure things like this out by yourself, you shouldn't be messing with this sort of things to begin with. I know that's not a nice thing to say, but it's a true one.
It may comfort you to know that if you make errors, that's okay. We've all made them at some points. I just suggest you learn to deal with them, rather than come crying for help at the first indication of something that may not be 100% clear from the start.