I assume you know a bit of HTML...
rather than filling your html with <font> tags and varous other ones concerned with layout you can write a CSS which makes managing all of this nice and easy. For example you could create a class called myFont within the CSS and then use the tag <p class ="myFont">
Now anytihng within that tag follows the rules laid out in the myFont class - it just saves you defining styles every time you use them.
...Saves loads of time and space if all of your pages follow the same style.
dont know if that was very clear, but if you do a google and look for some examples it'll probably make a bit more sense