Often times at first glance a board looks straight and the fact that it is actually bowed or has some warping isn’t always obvious. So the trick to knowing for sure, is to hold the board up towards your face, with the other end on the ground, and look at it at a downward angle (as shown in the below photo). This method will allow you to see if it is bowing at all.
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.