How can I add a background image to an email signature?

I was able to create an HTML file where I used an image as a background but as I tried to add it in Gmail (using what I found online which is opening the HTML file in a browser and copy-pasting it to the email signature field in Gmail), the background image won't show.

Another problem is that I used social media icons as well but they didn't load.

<table  width="600px" height="150px" border="0" cellpadding="16" cellspacing="0" background="Email Signature.png">
    <tr>
        <td valign="bottom" width="250px">
            <a href=""><img src="facebook.png" width="16px" style="padding-right: 8px"></a>
            <a href=""><img src="twitter.png" width="16px" style="padding-right: 8px"></a>
            <a href="" width="16px" style="padding-right: 8px"></a>
            <a href=""><img src="linkedin.png" width="16px" style="padding-right: 8px"></a>
        </td>
        <td valign="middle">
            Name, etc.
        </td>
    </tr>
</table>