A board is considered “quarter-sawn” when the growth rings run, more or less, perpendicular to the face of the board. Quarter-sawn boards generally have straight grain and are less prone to shrinkage, compared to other boards. These factors don’t come into play with the 2x4s you use to frame a closet—but it does with the shelves and cabinetry you put into that closet; you want those boards to remain straight, flat and stable.
The procedure is very easy to understand and follow for anyone with a little woodworking knowledge. Make sure to collect all the items you need before you start with the project. You may even ask Tracy your queries directly in the comment section of the tutorial post. Or you can ask them here. Either way, I hope that you manage to build this one nicely.