how to see web history in my sons iphone from my iphone

I don't believe there is a way to see the browing history on his phone from your phone using Safari. You might want to look at some of the alternative browsers which are designed with more parental controls. McGruff gets mentioned alot. You can install one of those browsers and disable Safari in restrictions. It's possible that one of them might have a feature your looking for.

You'd also want to disable downloading of any apps as your son could just download a different browser. And, for what it's worth, many apps have built in browsers.

Best of luck.

Open safari - click on the icon that looks like a book - history.