advice blocking/slipping overhand right/ usefull tipss

[destroyer32]

I am 15 years old and have recentley spent over 200 $ on boxing equiptment (2pairs of 14oz glove and 2 12s heavy bag punching mits ect..) I'm going to box (for fun) another kid he has more experience fighting but has no technique I've seen him fight before he is very scrappy but he windmills and loves to throw that overhand right over and over, its lightning fast but you can see it coming from a mile a way. I've got reach but he is shorter and stockier maby 15 to 20 pounds on me. I was wondering how to slip that overhand right or counter it. What about techniques for fighting people who windmill or just thro heavy for the hills. I fight southpaw he is orthodox. And what about footwork should I circle around him if so which way?