This article gives a very clear explanation of how to layout your page using the ‘float” property. Here is a highlight from the content available at the link below:
“…float is not a positioning property in CSS —the only position properties in CSS are absolute, relative, fixed, and static—however, when you combine widths, margins, and floats, you have CSS properties at your command that are often more reliable in terms of layouts than any of the available position properties. You can create all sorts of layout arrangements with float, whether or not float is technically a positioning property.”