You can add a border line to your Word document by following these steps:
1. Open the Word document.
2. Click on the “Page Layout” tab in the top menu.
3. Click on the “Page Borders” button in the “Page Background” group.
4. In the “Borders and Shading” dialog box, select the “Page Border” tab.
5. Choose the border style that you want to use from the “Setting” section. You can choose a solid line, a dashed line, or a dotted line, among others.
6. Select the width of the border that you want to use from the “Width” section.
7. Choose a color for the border from the “Color” section. You can choose a standard color or click “More Colors” to select a custom color.
8. Select the position of the border from the “Apply to” section. You can choose to apply the border to the entire document, the first page only, or a specific section of the document.
9. Click “OK” to apply the border to the document.
Note: The specific steps and options may vary depending on the version of Word you are using.