Install the Firefox browser and the Web Developer plugin for Firefox. You can use those to see where in the stylesheet you change the styling of the various page elements.

Ctrl-Shift-Y will allow you to hover over a section of the page and see the class and id names for that section in the box at the top. The statements in the stylesheet that begin with # are id's and the ones that begin with dots are classes.

Ctrl-Shift-E will open the CSS editor and allow you to edit the stylesheet and see the changes in real time without changing anything permanently. A very handy tool.

The sideboxes, for example, have their own id's, so you would find, say, #information in the stylesheet (or add it if it doesn't exist). To change the header of that box would be #informationHeading, the content area would be #informationContent, etc.

CSS is case-sensitive.