Changes to layout are done by CSS

Here is one good option:
1 install Mozilla firefox( if not already)
2 download and install the firebug add-on
3 right click on any item on your web page you want to change the layout for, and select "inspect element"
4 note the css values
5 go to your stylesheet and edit them.

This is the method I use to discover which CSS selectors control the layout for any given element.