Setting up umbraco

hello i am trying to set up umbraco on my pc

i have followed each step

and when i try to lunch the site on iis i get this error

Module IIS Web Core Notification BeginRequest Handler Not yet determined Error Code 0x80070032 Config Error The configuration section 'system.web.extensions' cannot be read because it is missing a section declaration
Config File \?\C:\inetpub\wwwroot\cms\web.config Requested URL http://localhost:80/cms Physical Path C:\inetpub\wwwroot\cms Logon Method Not yet determined Logon User Not yet determined

any idea? please help

Try changing the version of .NET that the application pool is running under.

You've not mentioned which version of Umbraco you are using but I'm guessing 4.7.

If so you'll probably need to be running it under .NET4, unless you have specifically downloaded the .NET3.5 version direct from Codeplex.