[news.eclipse.tools.emf] Adding elements to model

[ingelin.isfeldt@xxxxxxxxx (ingelin)]

I am new to EMF and working on a Sudoku thing using EMF (ecore) and TEF.
In my model, a Puzzle contains Field (types are Row, Column and Box).

I need to add elements to the model programatically by overriding the 
check method. The model alreay contains 9 rows, this is handled in the 
textual editor created in TEF. I need to create 9 boxes and 9 columns.

@Override
public String check(IModelElement modelElement, SemanticsContext context) 
{ 
  //own code
       Puzzle puzzle = 
(Puzzle)((EMFModelElement)modelElement).getEMFObject();

	NewstructureFactory factory = NewstructureFactory.eINSTANCE;

	Box b1 = factory.createBox();	 
}

How can I add this box to puzzle?