Getting the following Error when code is moved to a web server

Getting the following Error when code is moved to a web server

I get the following error
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 14: <customErrors mode="Off"/>
Line 15: <compilation debug="true" targetFramework="4.0"/>
**Line 16: <authentication mode="Forms">**
Line 17: <forms loginUrl="~/Account/Login.aspx" timeout="2880"/>
Line 18: </authentication>
and LINE 16 is the source of ERROR. This is my first deployment of code
and not sure what needs to be corrected. Any help is appreciated.