create my subdomain

when i go to create my subdomain iphone.mydomain.com ,I have to enter a folder path. What is?
Thank you very much for this great add- 

The same value as your main site (mydomain.com) has.

I have done so. But it has created an empty folder called iPhone on the server.
Do I have to do anything else?

ps :  site is  www.gemmahervas.com/

What control panel is used by your hoster?

I think it is proper, the company is dinahost