Alex,
PT-40 is an easy building model. When in doubt or if you have a question, just ask. RCU is a good place to get your questions answered. Most people whom answer to questions are experienced builders or have built a PT40 that has been flying. I learned to fly in a PT-40 I built five years ago.
Enjoy your build. Always wear personal protective equipment0, i.e. dust mask, when sanding balsa or any wood.
WARNING: Building model airplanes is addictive. [X(] Caution must be taken to avoid excessive hours in the shop.