There is an "add existing item" option:
- right-click on a directory
- select Add | Add Existing Item
I don't know if this will copy the files to where you want them.

Or you can use this:
- copy the cs files to the project directory where you want them
- select the "show all files" option at the top of the solution explorer
- possibly use the "refresh" button, also at the top of the solution explorer
- go to the directory where you added the files (they show in grey)
- right-mouse, select "add to project"

Hans Kesting