Ibook, how to create a subfolder

My definition of a sub folder is; A collection of a similar topic, the question that brings up is, does the subfolder need to be closed or, can it remain an open subfolder. Well, as I have found out the hard way there are no regular type subfolders in Ipad/Ibooks so, what is working for me is;

Within the folder/collection is to create an numerical alphabetic system

1. Create collection title in this case we'll use "TOOLS"

2. This involves the following sub titles/folders; Hand tools, electric tools, air tools, micro tools, electronic tools which, books or pdf's are dropped in the collection. Next is layout

1. A HAND TOOLS origin of the hammer

1. B Screwdriver

1. C Allen key

2. A ELECTRIC TOOLS Drill

2. B Table saw

3. A AIR TOOLS Air gun

3. B Air drill

3. C --------

4. A MICRO TOOLS

5. A ELECTRONIC TOOLS

I know too many that the titles might not be exciting but, they were used to make it simplistic. Okay, once this done and one wants to see the subfolder in an organized layout hit AUTHORS.

There is one problem that maybe someone out there can help me with, sometimes on a pdf download I will get in light grey an author, logo or something similar that will not allow that file to join my numerics. I would really like to find a way of deleting it

Hope this helps

have a g'day all