Laying out a Web page exactly how you want it so that it works in every browser and every screen size is the biggest challenge in front-end development (Web design, Web creation or Web authoring).  Most of the problems and solutions are to do with positioning various boxes.

You already know how to create boxes (elements such as div, nav and p) and how to set their margin, padding and border.  These pages are about how to use those things and size to control their position.