Creating one was the easiest. At this stage instructures asked us to change the grid without adding or erasing but moving and cutting lines. I wish I had known the systematic way of organizing a grid.
Since I did not have that much of a detailed grid, I finished it with ease without knowing that I have left the grid concept (actually I was not aware of the grid concept itself anyway). Afterwards, in addition to moving and cutting operations, rotating, adding and deleting were added. I did not use rotating (I thought it was risky in my case) but adding and moving.