New to DNN. Tried to install following the instructions as detailed, but keeps getting this error '

I have done all that is shown on the error, yet it persists

I am using windows 7 , sql server express, and DNN 5.5 install package

The error is as follows :

DotNetNuke Configuration Error

Access to the path 'D:\DotNetWeb\DotNetNuke\web.config' is denied.

DotNetNuke has extensive file upload capabilities for content, modules, and skins. These features require custom security settings so that the application is able to create and remove files in your website.

Using Windows Explorer, browse to the root folder of the website ( C:\DotNetNuke by default ). Right-click the folder and select Sharing and Security from the popup menu ( please note that if you are using Windows XP you may need to Disable Simple File Sharing before these options are displayed ). Select the Security tab. Add the appropriate User Account and set the Permissions.

• If using Windows 2000 - IIS5
  
  1. the [SERVER]\ASPNET User Account must have Read, Write, and Change Control of the virtual root of your website.
• If using Windows 2003 - IIS6
  
  1. the NT AUTHORITY\NETWORK SERVICE User Account must have Read, Write, and Change Control of the virtual root of your website.'

Thanks. Please can you enlighten me on how I can remove all the modifications I have made so I can start afresh ie in SQL Managemnet studio, IIS etc?

I don't know how to do that except by uninstalling iis and sql server through add/remove programs