Error in web.config

hai, i am trying to add functionality of DotNetNuke CMS with NopCommerce project my error is

Parse error:
It is an error to use a section开发者_如何学C registered as allowDefinition='MachineToApplication' beyond application level.  This error can be caused by a virtual directory not being configured as an application in IIS.
<customErrors mode="RemoteOnly"/>
 <!-- Forms or Windows authentication -->
 <authentication mode="None">
 <forms name=".DOTNETNUKE" protection="All" timeout="60" cookieless="UseCookies"/>
 </authentication>

I dont know how to find virtual directory in iis7 and configure our application. please help me.

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If you go to IIS 7 and find your website. Right mouse click the folder where your content is and click "Convert to Application".