[Solved]Copy a complete Projektmappe

I try to simply copy a project or to create a new peoject by save as....

But I fail. Sorry, to be so stupid.

To explain ist, first a short remark. In german version you have a Datei (file?) and a Projekt (project?) and a Projektmappe (solution? or project folder?) 

I habe opened a Projektmappe (solution) (everything works fine), name "test1"

To improve it, i wold like to keep the solution, but expand it under name "test2"

I try to take "save as" - but i get a file stored, not an Projektmappe

I try to create a new Projektmappe "test2" and to copy my "test1"  into it. its not a success

I try to copy my folder "test1" in the explorer, rename all files from "test1" to "test2", but i cannot open then "test2" Projektmappe.

What is the best, easiest, simplest, fastest way to copy a Projektmappe. It should not be so complicated ??