These yellow boxes are explainer boxes. They explain things like you're five. I know you're much smarter than a five-year-old but sometimes starting with small words is better. Small words make it easier to decide if you want to read all the fancy grown-up words. You can close these yellow boxes if you want to.
Also, the little blue thingies have more explainy words. They look like links to other websites but they're not. Links, images, blue thingies... they all have explainy words if you hover over them. All you have to do is hover over them. So you may want to use a mouse.