Final answer:
To cover a whole page with a background image, use CSS to set the desired image as the body's background. The 'background-size' property set to 'cover' ensures the image fills the entire space. Drag and drop can be used for uploading the image.
Step-by-step explanation:
To add a background image that covers the entire page, you can use CSS (Cascading Style Sheets). This would involve using the background-image property. You can also set additional properties such as background-size to cover to ensure the image covers the whole page, as well as background-position and background-repeat for fine-tuning.
For the image file, the drag and drop method mentioned allows you to easily upload the image to your directory or hosting service. After the image has been uploaded and is ready to use, you would apply it as the background via CSS.