Navigate to Settings > Layout to start the layout editor.
At Layout > Color palette you can choose from a number of predefined color palettes. These are the standard colors that your website will get. When selecting a color combination, you will see the result immediately.
At Designer > Color palette advanced you can change all the colors separately.
At Designer > Text color you can change the foreground color and the background color of your texts.
Do not set the foreground and background colors to the same or to a similar color: if there is no or little contrast, the texts will not be visible or they will be difficult to read.
At Designer you can also change the Title Color, Price Color and Links - Color to personalize the colors of the titles, prices and hyperlinks.
Don't mix too many colors, this comes over as very unprofessional. Stay consistent in your colors and make sure that everything is readable.