For completing this you can create an new contact item under contacts. Now select all the contacts you want to export with ctrl + click. After selecting all the contacts press CTRL + C (to copy the contacts) and go to you new contact folder. In the new contact folder press CTRL + V (to paste the contacts).
After this is done you can go to: File -> Import & Export. Select Export to a file.
In the next screen select Comma Separated Values.
Now you can select the new created contacts folder and export the contacts you pasted in there.