Applying a style to a selection of text, such as a title, heading, or paragraph, in Word is as easy as clicking a button in the Styles gallery.
Select the text to which you want to apply a style.
For example, you can select text that you want to make into a heading. If you want to change the style for an entire paragraph, click anywhere in the paragraph.
On the Home tab, in the Styles group, click the style that you want. If you don't see the style you want, click the More button to expand the gallery.
You can see how selected text will look with a particular style by placing your pointer over the style that you want to preview.
Note: If the style that you want does not appear in the gallery, press CTRL+SHIFT+S to open the Apply Styles task pane. Under Style Name, type the name of the style that you want. The list shows only those styles that you already used in the document, but you can type the name of any style that is defined for the document.