I am running the newest version of Peppermint in VirtualBox,but this is a general Linux question.
I want to easily copy a file (using nemo-the file explore app in Peppermint) from a shared folder and use it. I figured out a method,but was wondering if there is an easier way. From my personal notes,this is how I currently do it:

1) I am in peppermint and want copy a file from vshare (Shared Folder with host) to MY desktop ("ME")-not the "root" desktop.
2) open Menu-Files
3) right click and "Open As Root"...this brings up a new file manager (called nemo in Peppermint,called nautilus in Ubuntu).
4) in the new file manger you have root access... goto the vshare (the folder you are sharing-IF YOU DON"T SEE IT YOU ARE NOT ROOT) folder. Highlight and Copy the file.
WHEN YOU ARE ROOT-the file manger will say "Elevated Privileges"
5) bring up yet another file manager-not as root-just a normal "ME" file manager. In this one navigate to /home/ME/Desktop
6) right click "Open As Root" Now drag and drop the the file into this folder (or Paste)
The file is copied and you should see it on the desktop (/home/Desktop) BUT the damn file is locked! So....
7) While still in this file manager, right click File-Permissions and change Access to "Read and write"
FINALLY! You can now read and write the file. There has to be an easier way!

Thanks in advanced!

tl;dr
do you want to copy files from the virtual machine to the host?
that is not so easy indeed.

if you talk about copying files inside the linux os, i don't see why it should be so difficult. tell us exactly which files from where to where (full path).

you got a share directory that you set up in VBox. It is a directory you can create or use one that is already created, located on the host side. Then connect it via the set up selection for what ever install you are using in Vbox so the client can get to it, so you can move files between the client, and host, and visa versa. Root privileges should not ever be needed if you set it up properly.