To help with the explanation of a grid layout we have some visuals from a student, Joana Koiller, who makes use of grid work in all her layouts and spreads.
She had 12 columns that she aligns all of her text boxes, visuals and titles to.
But she has fun with the grid and does not get mired by it.
Take a look.
EDIT: OKAY, I realized it is very hard to see the lines, Until i can remedy this just click on the image to enlarge it and you will be able to see faint blue guide lines. Never the less, one can see the pattern that emerges from keeping the text and image uniform on grids. Well Done.