Forum Academy Marketplace Showcase Pricing Features

Scrolling Content in a Group

What is the simplest way to make a Scrollable Group? So lets say my “inner” in 1500px but the “outer” is only 500px so I can scroll it 3x times in the end. I have found one example but it does not really explain it in a generic way…
In CSS Tutorials they called it Scrolling Overflow I guess - however I don’t know any CSS etc. so need an idiot proof explanation. And I also would like to just do it everywhere in my page, with just 2 rectangles. In WIX that’s 1second job…

Is there a more detailed tutorial? Simpler way?