How to add a line in word is to add a line in the blank.

1. First open the Word document, click the "Insert" option in the toolbar at the top of the document page, and find the "Shape" icon.

2. Then click the drop-down box of "Shape" and select the first style in "Line" in the options.

3. Then use the mouse cursor to drag a line in the blank space of the page.

4. You can click Shape Outline to change the color, line type and thickness of the insertion line.