Daily calorie intake on weight training vs Non training days

imsotall

I am about to start a beginners 4 week weigh training program (3 days per week initially) that I found on the Muscle & Fitness website

My question is... if I am supposed to eat 1700 calories on a normal day how much should I increase this by on days where I go weight training?

Also, if I am supposed to eat more on a training day. Is this just to ensure my overall daily calorie intake balances out at the end of the day or is that additional food (especially the protein) actively used by my body to build additional muscle (that I wouldn't get if I didn't eat that extra food) - I am assuming it's a bit of both.