First of all, style the body font size! Remember to select "Body (All Pages)" or for example "Heading 1 (All Pages)" for all elements except the components and buttons.
You'll see that these typography elements don't have classes. That's because on this page, we want to edit the styles after selecting "All H1 Headings" for example, so that it will effect all the elements on the site. To do this, select the H1 below, click where it says "Select a Class or Tag" and select "All H1 Headings" at the bottom of the list.
These colors have been created using Global Swatches. If you edit the Global Swatch color, it will change every element that uses that color swatch.