scrolling through emails on Mac

Hi!

I recently got a used MacBook Air. I have previously been using an older Macbook with a mouse, and daily, my iPhone to check email. I haven't been able to figure out how to scroll up or down through my unopened email list without first having to click on it and arrow up or down through the list, which then opens it! There has got to be a way to scroll through without having to open each email!!! Please help!!!