如何添加一个链接到一个网站的按钮和回到应用程序

I was wondering how to add a link to a website so that when the user taps on a button, he will be taken to that webpage, but can then hit an x in the top left corner or hit the home button and then it will take them back to their app. I want it to be like iad where it doesn't close your app when you click on that link.I was wondering how to add a link to a website