When you upload a document, don't specify the MIME type. Specifying the MIME type may trigger a bug in the enotebook software.
After uploading, the enotebook software should set the MIME type automatically based on the filename extension of the file you uploaded. (This assumes that the browser you're using for the upload understands the MIME type for that extenstion.)
When you have more than one page in your notebook, the Contents button at the top of every notebook page will let you navigate to any other page in your notebook.
I do not make regular backups of these notebook pages, so please keep a copy of any document you post in your notebook.
(junk notebook to experiment with)
This document was generated using AFT v5.0792