How can i make a image to fit

Can someone help me please with my problem. I dont know very good about html i have found some code to solve it but i cant use them i dont know where exact开发者_如何学运维ly to form them. I want to make the imcage fit to each users resolution and dont appears right and down of their screen white boxes. I want to fit 100% in window. I hope you understand what i mean. My code is this.

<style>
<!--
BODY {background-image: url(bg_body.jpg); background-repeat: no-repeat; }
-->
</style>

i hope you can help me thanks in advance

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Is this what you are looking for?

<img src='whatever.png' style='width: 100%; height: 100%' />

This will make the image fill its parent container.