On the Design tab, point to one of the style sets in the Style Sets gallery in the Document Formatting group.
The new style set is previewed in your document's existing text.
Click the style set you want.
If you don't like any of the choices displayed, click the More button for the gallery to open the full gallery of choices. Notice that you can reset to the default style set from this gallery menu, or save the current settings as a new style set.