Based On details in The comments it seems that you are running from a windows machine using putty. Due to limitations with the putty connection, You would need
x forwarding to use a native terminal to have multiple tabs (as your putty terminal each tab is a separate connection, controlled by windows rather than being a single point of access to the linux machine). As a result your best option is to use an editor that has built in tab support (which to my knowledge nano unfortunately does not). If you are up for using vim as an alternative, it does support tab's as an option.
You can open all your items in vim in separate tabs with
vim -p *.cpp
then control them further with the following:
:tabe <file> #Opens <file> in a new tab
:tabp #Switches to previous tab
:tabn # switches to next tab
Alternatively you can use window splits
:split # Opens a second editor in a horizontal split
:vsplit # Opens a second editor in a vertical split
ctrl-wctrl-w Jumps between splits.
Or Multiple buffers
:e <file> #edits opens <file> in a new buffer
:bn # switches to the next buffer
:bp # switches to previous buffer
The real usage would be a combination of all three. Us multiple tabs to have different configurations of window splits for different purposes, and switch window split buffers between different buffers as you need them.
As a final Alternative, if you download an ssh client that supports x forwarding, I use mobaXterm You could run something like gnome-terminal (Assuming you have, or can install a Window Manager) as a GUI program from the Linux system, and possibly get your tab solution that way as well.