Public Sub WriteXml()
        Dim doc As New XmlDocument
        Dim RootElement, IDElement As XmlElement
        Dim xmlAtrib As XmlAttribute
        Dim Declar As XmlDeclaration
        Dim comment As XmlComment
        Dim i, n, res As Integer
       

        Declar = doc.CreateXmlDeclaration("1.0", Nothing, "yes")

        doc.InsertBefore(Declar, doc.DocumentElement)
        comment = doc.CreateComment("Create with the XmlDocument class ")
        doc.InsertAfter(comment, Declar)

        RootElement = doc.CreateElement("ArrayKvit")
        doc.InsertAfter(RootElement, comment)

        n = _ID.Length

        For i =  0  To n -  1 
            res = _ID(i).ToString
            IDElement = doc.CreateElement(_CartID)
            IDElement.InnerText = res.ToString
            RootElement.AppendChild(IDElement)
        Next

                doc.Save("C:\Inetpub\wwwroot\RegDB\ArrayKvit.xml")
        
End Sub

Access to the path "C:\Inetpub\wwwroot\RegDB\ArrayKvit.xml" is denied. 
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.UnauthorizedAccessException: Access to the path "C:\Inetpub\wwwroot\RegDB\ArrayKvit.xml" is denied. 

ASP.NET is not authorized to access the requested resource. Consider granting access rights to the resource to the ASP.NET request identity. ASP.NET has a base process identity (typically {MACHINE}\ASPNET on IIS  5  or Network Service on IIS  6 ) that is used if the application is not impersonating. If the application is impersonating via <identity impersonate="true"/>, the identity will be the anonymous user (typically IUSR_MACHINENAME) or the authenticated request user. 

To grant ASP.NET write access to a file, right-click the file in Explorer, choose "Properties" and select the Security tab. Click "Add" to add the appropriate user or group. Highlight the ASP.NET account, and check the boxes for the desired access.

Source Error:  и так далее