Yeah you need to reformat.
I don't know what softmod guide did you follow, but if you want help, you'll need to do it all over again. Go here http://www.wiihacks.com/recommended-...d-any-wii.html
And follow it. Don't format the wii or anything, just follow that guide. If you already have HBC, it's gonna be a lot easier.
When you're done with re-softmodding, format the whole hard drive to FAT32. No partitions what so ever.
When you did that, put all your files on the root of the HDD. The same way it would be on the SD card, but delete everything in the USB Loader GX folder except boot.dol, meta.xml and icon.png.
You are now good to go, just plug it in your wii and click the little plus on the lower left part of the screen and add the game.
If you have any ISO backups on your computer, make a folder called "WBFS" on the root, without the quotes, and then use Wii Backup Manager to add games like you would normally.