Assuming you mean Word 2007...
Click on Mailings | Labels | Labels tab | Options | Label vendors: Avery
US Letter | Product number: 8877 | OK | New Document. If you can't see
the text boundaries of each business card, click on Table Tools: Layout
| View Gridlines. Type what you want into one of the business card
boxes, and when you're done, copy and paste to the other boxes.