Hi guys, I hope you're good !

I have a little question about how to make something similar like this website:http://www.brianhoffdesign.com/index.html

I searched everywhere but I can't find the solution. I know it's not hard to do. Basically it's a one page. We show only a div parts then we hide this div and we scroll to the other div, then we fix the menu on top. But I tried to do that without working! Anyone may help?

Thanks !