Not able to install dotnetnuke in my windows vista system

I am trying to install dotnetnuke in my system. For that i have unzipped dotnetnuke installable zip at C:\inetpub\wwwroot\DotNetNuke and created this directory as virtual in iis. Any other than this i have to do to successfully install ddn. How to create and attach database with it. Currently i am gettting below error.

Server Error HTTP Error 500.19 - Internal Server Error

Description: The requested page cannot be accessed because the related configuration data for the page is invalid.

Error Code: 0x80070021

Notification: BeginRequest

Module: IIS Web Core

Requested URL: http://localhost:80/dotnetnuke

Physical Path: C:\inetpub\wwwroot\DotNetNuke

Logon User: Not yet determined

Logon Method: Not yet determined

Handler: Not yet determined

Config Error: This configuration section cannot be used at this path. This happens when the section is locked at a parent level. Locking is either by default (overrideModeDefault="Deny"), or set explicitly by a location tag with overrideMode="Deny" or the legacy allowOverride="false".

Config File: \?\C:\inetpub\wwwroot\DotNetNuke\web.config

Config Source:

79: 80: 81:

More Information... This error occurs when there is a problem reading the configuration file for the Web server or Web application. In some cases, the event logs may contain more information about what caused this error. Server Version Information: Internet Information Services 7.0.

Microsoft has a tool called Webmatrix which makes it very easy to install DotNetNuke (and other applications).