Paste it wherever your site lets you add HTML. On Squarespace, Wix, Shopify and WordPress that is usually a footer or custom code block.
<a href="https://mackaybusinessguide.com.au/" title="Listed in the Mackay Business Guide"><img src="https://mackaybusinessguide.com.au/assets/badge.svg" alt="Listed in the Mackay Business Guide" width="270" height="48"></a>