Each style can be applied to a particular HTML page element such as a heading or a paragraph. Then, you could create new page elements and apply style attributes to them, just as you would to regular HTML page elements. That way, for example, you could change the indent on all your indented paragraphs without affecting the regular paragraphs. You can't create your own HTML tag names. But you can create classes of HTML element, and apply a style to all those classes.
Tips have a gray background, a ten-pixel indent, and red type.
You could apply those styles to indicate paragraph tags, but if the tip design changed, you'd have to go back and change each tip. You'll want to do this to every paragraph that will be used as a tip. Once you have a class of page element, you can apply styles to that element by name as you would any other HTML tag. In the style sheet, simply refer to the name of the paragraph and the name of the style together. For tips, the style would be P.Tip.