Build a form widget: Implement the template 
By definition, your widget must provide UI for both displaying and editing the value of a
widget. 
 EXAMPLE: For more information about the markup of the widget, see FormWidget.ascx in Sitefinity documentation-samples on GitHub.
This template does the following:
    - Registers the Telerik.Sitefinity.Web.UInamespace, to use theSitefinityLabel.
- Includes only the required labels for TitleControl,DescriptionControl, andExampleControl.
 These IDs correspond to the IDs that are used in the class properties.
By following the example above, you have a blank template, where you can add the custom controls for your field control.