The first post of
Quick Guide to Shelf Management with calibre 0.9.1 & above describes what you need to do. And to create a shelf for each author, add "author" as one of the shelf columns in the driver configuration. If you have followed those instructions and it isn't working, we'll have to look at why.
If the problem is how to set the shelf column in the calibre library, it takes work. But, you can select all the books you want to set the value for and use the bulk metadata editor. Once you have done that, connecting the device will update the shelves on the device.
As to nested shelves, the Kobo doesn't do them. Just the single level.