you can use the Microsoft.Web.Administration to control IIS7, you need to add the file Microsoft.Web.Administration.dll to your project.
also your application need admin access.

thanks but i got this error while compiling:

Warning 2
The referenced assembly "Microsoft.Web.Administration, Version=7.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL" could not be resolved because it has a dependency on "System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" which is not in the currently targeted framework ".NETFramework,Version=v4.0,Profile=Client". Please remove references to assemblies not in the targeted framework or consider retargeting your project.

and this error too:

The type or namespace name 'Web' does not exist in the namespace 'Microsoft'

try changing the TARGET FRAMEWORK from .NET 4 Client Profile to .NET FRAMEWORK 4

it works, but how i grant permission from the visual studio ?

"Cannot read configuration file due to insufficient permissions"

i found this solution :
1. Add IIS_IUSRS with Read permission on files in the folder
2. Change IIS authentication method to BasicAuthentication
3. refresh the website.

but i'm using a webform not a website or wcf.

if you run Visual Studio with administrator previleges, you application will have the permissions too.