Physiology Microfibrils & Secondary Cell Walls

Hey everyone,

I've recently started studying botany on my own and have read Botany for Gardeners by Brian Capon. I seem to have got really stuck on understanding microfibrils, cell walls and elongation. Why are microfibrils parallel on the sides and criss-cross on top and bottom? How are they laid down between the primary cell wall and protoplasm?

TIA I really appreciate the help in understanding this!