Uploading files to Jupyter running on VM VitualBox
Yes, it's possible. 
To begin with, your host PC mut have a shared folder with your VM (Explained elsewhere).
A method I do is to
First create a folder myfolder for the (.pdf or .csv) files.
Secondly, load the folder by: going to the created myfolder  --> right-click on the myfolder --> choose "Open in Terminal".
Thirdly, at the terminal it should look like this: myfolder]$. Then I type "jupyter notebook" as such: [username@localhost myfolder]$ jupyter notebook and hit ENTER. 
The folder should be opened and containing my .pdf or .csv files.
Is it possible to upload a file (say a .pdf or .csv) saved in my hard disk into Jupyter running on VirtualBox?