访客回到网站后弹出窗口不显示

I have created a very simple popup window. What I would like is when the visitor come to the website for the first time to show the popup and he will have to choose one of the two buttons in order to close the popup. Moreover, I would like to do not show the popup box when the user has visited the site before. I know that I can use localstorage for that but I do not know the technique. Please, I need someone to write me the localstorage code that I have to add in my code so that when someone visits the website for the first time to show the popup and choose one of the two buttons, and if he comes back again to do not show the popup using localstorage memory.I have created a very simple popup window. What