Assuming you are using Microsoft Excel:

1. Open your browser of choice (Internet Explorer, Firefox, Safari, etc.)
2. In the top navigation bar, click on "File" and then "Open"
3. A new window will pop up. In the "Open" field, type in the URL of the website you want to open in Excel. For example, if you want to open Google, you would type in http://www.google.com
4. Click on the "Open" button.

Your website should now be open inside of Excel!