Select the text whose line spacing you want to alter or press Ctrl+A to select the entire document. (Notice the text on this page fills only two thirds of the page.)
Click the down arrow next to the Line Spacing button on the Formatting toolbar and select a line-spacing option (in this case, 1.5). For more spacing options, select More.
The line spacing is altered such that the text in the document fills the entire page.
INTRODUCTION
Have you ever found yourself in a situation where you needed to fill up a page with text but just couldn't think of any more text to write? Line spacing can be a handy tool that can increase (or decrease, if needed) the amount of vertical space between lines of text so you can stretch two-thirds of a page to fill one whole page.
TIP
Spacing Above and Below
Word uses single-line spacing by default. You can also alter the amount of space above or below a line of text. To do so, open the Format menu and select Paragraph to open the Paragraph dialog box (click the Indents and Spacing tab if you aren't already there). Click the spacing you desire in the Line Spacing drop-down list and alter the numbers in the Before and After spin boxes.