i think esox has covered it. you want to fish a venue with alot of fish in so you and your son can have a good result. you will often see the float wobble as fish inspect the bait, if it goes under you have a bite so lift the rod tip slightly (strike) to hook the fish. dont strike too late as its possible for a fish to swallow the hook, but keep an eye on your float and pull your bait in when helping your son it wont happen. i would fish maggots as all fish love these, it may be worth buying a catapult to fire the free feed out to where you want to fish, you can get one for a few quid from most tackle shops. feed little and often until you get bites, you will entice the shoals of fish to your area, keep feeding when they're there too.
when you are fishing dont be afraid to ask other anglers for advice as most are more than willing to help. same with websites like maggotdrowners
you should enjoy it its a very relaxing past time