Create the code-behind

To do this, perform the following:

1. Add a class and name it MyCustomSettings.cs
2. In the class, paste the following code:

   	using System.Web.UI;
   	using Telerik.Sitefinity.Web.UI;
   	using Telerik.Sitefinity.Web.UI.Fields;
   	namespace SitefinityWebApp.CustomSettings
   	{
   	public class MyCustomSettings : SimpleView
   	{
   	#region Properties
   	/// <summary>
   	/// Obsolete. Use LayoutTemplatePath instead.
   	/// </summary>
   	protected override string LayoutTemplateName
   	{
   	get
   	{
   	return string.Empty;
   	}
   	}
   	protected override HtmlTextWriterTag TagKey
   	{
   	get
   	{
   	//we use div wrapper tag to make easier common styling
   	return HtmlTextWriterTag.Div;
   	}
   	}
   	/// <summary>
   	/// Gets the layout template's relative or virtual path.
   	/// </summary>
   	public override string LayoutTemplatePath
   	{
   	get
   	{
   	if (string.IsNullOrEmpty(base.LayoutTemplatePath))
   	return MyCustomSettings.layoutTemplatePath;
   	return base.LayoutTemplatePath;
   	}
   	set
   	{
   	base.LayoutTemplatePath = value;
   	}
   	}
   	#endregion
   	#region Control References
   	/// <summary>
   	/// Reference to the Label control that shows the Message.
   	/// </summary>
   	protected virtual ChoiceField RandomVariable
   	{
   	get
   	{
   	return this.Container.GetControl<ChoiceField>("randomVariable", true);
   	}
   	}
   	#endregion
   	#region Methods
   	/// <summary>
   	/// Initializes the controls.
   	/// </summary>
   	/// <param name="container"></param>
   	/// <remarks>
   	/// Initialize your controls in this method. Do not override CreateChildControls method.
   	/// </remarks>
   	protected override void InitializeControls(GenericContainer container)
   	{
   	this.RandomVariable.Choices.Add(new ChoiceItem { Text = "first option", Value = "first option" });
   	this.RandomVariable.Choices.Add(new ChoiceItem { Text = "second option", Value = "second option" });
   	this.RandomVariable.Choices.Add(new ChoiceItem { Text = "third option", Value = "third option" });
   	}
   	#endregion
   	#region Private members & constants
   	public static readonly string layoutTemplatePath = "~/MyCustomSettings.ascx";
   	#endregion
   	}
   	}

   view raw MyCustomSettings.cs hosted with ❤ by GitHub

NOTE: In the above class, you define the path to the template as virtual path.