Groups of cells in unstructured grid

I have to write vtk files using vtk library to write unstructured grids. And I need to create groups of cells according to type of cells (triangles, linees, etc) or materials (beams, shells, iron, etc…). Moreover, I would like to define properties to theses groups as name, colour and I would like identify these groups in paraview with these properties.

Which clases I should use? Dataset? FieldData? vtkMaterial? Filters?

Thanks very much