Your next assignment is to study how to layout elements in HTML and how to make those layouts responsive. Responsive web design refers to a website that has been created to change sizes depending on the size of the viewing device, this way your website will look great no matter what type of device it is being viewed upon.
Read, study, practice and create a simple 1 page HTML/CSS page that demonstrates HTML layout and responsiveness.
W3Schools - HTML Layout
W3Schools - Responsive Design