For both headlines and paragraphs, you have the option to choose the group of text that you want to change the color of. You can do this by clicking the Headline/Paragraph element and then clicking EDIT. Highlight the text(s), then click on the leftmost icon from the menu and select the color.
In order to change a shape’s background, click on it. This will open the menu on the right. Here you can select the background color:
For backgrounds, you can change the color for a block or the whole page.
Adjusting the background color for your whole page is done from the right-side Settings menu. Choose Page Background, then select the color you wish:
Alternatively, to modify the color only for a block of your landing page, click on the Block Style icon for the block in question: