Modularity-Creating An Irregular Grid

I'm a student and a grasshopper beginner trying to build an irregular but modular grid.

Basically, Im trying to break down a square grid by dividing one base unit into smaller modules and then randomly filling a prescribed space wih those units.

I found this, which is along the same lines but its a little hard to understand, especially in the "second quadrangular construction" definition.

https://www.box.com/shared/d6sik35vba

Any suggestions?