Im a new bee to Asp.net. I have encountered errors while running the subfolder("used as test folder")

Configuration Error
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.

Parser Error Message: It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level. This error can be caused by a virtual directory not being configured as an application in IIS.

Source Error:


Line 24: ASP.NET to identify an incoming user.
Line 25: -->
Line 26: <authentication mode="None"/>
Line 27: <customErrors mode="Off" />
Line 28: <!--