Demo for a modal dialog

We have been given a wireframe by an external design agency where data is presented in a grid. There is an image of a pencil in each row at the right hand side - when the user clicks it the record is presented in a modal dialog (over top of the grid) for editing.
How do I create a modal dialog in Web Core that I can invoke from a button - is it just another form ?
Is there a demo that I can view / copy.

You can use the technique as demonstrated in Demo\Basics\MultiForm that shows a code invoked secondary modal form.