show website when there are no internet connection (by using cache )

there are many website who show offline website too like first if you loaded your website in chrome browser before and later if there are no internet connection, then i am able to see website too for example check [login to view URL] in google chrome one time and then close your internet connection and check again [login to view URL] , you will be able to see the website , i want to do just like this for my website the task is small and it should be done in few hours only