' Create a custom section.
Shared Sub CreateSection() 
    Try

        Dim customSection As CustomSection

        ' Get the current configuration file.
        Dim config As _
        System.Configuration.Configuration = _
        ConfigurationManager.OpenExeConfiguration( _
        ConfigurationUserLevel.None)

        ' Create the section entry  
        ' in <configSections> and the 
        ' related target section in <configuration>.
        If config.Sections("CustomSection") Is Nothing Then
            customSection = New CustomSection()
            config.Sections.Add("CustomSection", customSection)
            customSection.SectionInformation.ForceSave = True
            config.Save(ConfigurationSaveMode.Full)

            Console.WriteLine( _
            "Section name: {0} created", _
            customSection.SectionInformation.Name)
        End If

    Catch err As ConfigurationErrorsException
        Console.WriteLine(err.ToString())
    End Try

End Sub 'CreateSection

// Create a custom section.
static void CreateSection()
{
    try
    {

        CustomSection customSection;

        // Get the current configuration file.
        System.Configuration.Configuration config =
                ConfigurationManager.OpenExeConfiguration(
                ConfigurationUserLevel.None);

        // Create the section entry  
        // in <configSections> and the 
        // related target section in <configuration>.
        if (config.Sections["CustomSection"] == null)
        {
            customSection = new CustomSection();
            config.Sections.Add("CustomSection", customSection);
            customSection.SectionInformation.ForceSave = true;
            config.Save(ConfigurationSaveMode.Full);

            Console.WriteLine("Section name: {0} created",
                customSection.SectionInformation.Name);

        }
    }
    catch (ConfigurationErrorsException err)
    {
        Console.WriteLine(err.ToString());
    }

}

' Define a custom section.

NotInheritable Public Class CustomSection
    Inherits ConfigurationSection


    Public Enum Permissions
        FullControl = 0
        Modify = 1
        ReadExecute = 2
        Read = 3
        Write = 4
        SpecialPermissions = 5
    End Enum 'Permissions


    Public Sub New() 

    End Sub 'New



    <ConfigurationProperty("fileName", _
    DefaultValue:="default.txt"), _
    StringValidator(InvalidCharacters:=" ~!@#$%^&*()[]{}/;'""|\", _
    MinLength:=1, MaxLength:=60)> _
    Public Property FileName() As String
        Get
            Return CStr(Me("fileName"))
        End Get
        Set(ByVal value As String)
            Me("fileName") = Value
        End Set
    End Property


    <ConfigurationProperty("maxIdleTime", _
    DefaultValue:="1:30:30")> _
    Public Property MaxIdleTime() As TimeSpan
        Get
            Return CType(Me("maxIdleTime"), TimeSpan)
        End Get
        Set(ByVal value As TimeSpan)
            Me("maxIdleTime") = Value
        End Set
    End Property



    <ConfigurationProperty("permission", _
    DefaultValue:=Permissions.Read)> _
    Public Property Permission() As Permissions
        Get
            Return CType(Me("permission"), Permissions)
        End Get

        Set(ByVal value As Permissions)
            Me("permission") = Value
        End Set
    End Property
End Class 'CustomSection

// Define a custom section.
public sealed class CustomSection :
    ConfigurationSection
{

    public enum Permissions
    {
        FullControl = 0,
        Modify = 1,
        ReadExecute = 2,
        Read = 3,
        Write = 4,
        SpecialPermissions = 5
    }

    public CustomSection()
    {

    }

    [ConfigurationProperty("fileName", 
        DefaultValue = "default.txt")]
    [StringValidator(InvalidCharacters = " ~!@#$%^&*()[]{}/;'\"|\\",
               MinLength = 1, MaxLength = 60)]
    public String FileName
    {
        get
        {
            return (String)this["fileName"];
        }
        set
        {
            this["fileName"] = value;
        }
    }

    [ConfigurationProperty("maxIdleTime", DefaultValue="1:30:30")]
    public TimeSpan MaxIdleTime
    {
        get
        {
            return (TimeSpan)this["maxIdleTime"];
        }
        set
        {
            this["maxIdleTime"] = value;
        }
    }


    [ConfigurationProperty("permission", 
        DefaultValue = Permissions.Read)]
    public Permissions Permission
    {
        get
        {
            return (Permissions)this["permission"];
        }

        set
        {
            this["permission"] = value;
        }

    }

}