This looks a bit crazy, but below is one way to do it. Paste it into a new dashboard. I am assuming you have some background knowledge of how to do HTML/CSS. Otherwise this will be very hard.
<dashboard>
<label>TestDashboard</label>
<row depends="$hide_this$">
<panel>
<html>
<style>
#background_table {
background:url(https://i.imgur.com/ZodtLh7.jpg);
}
#background_table th, #background_table td, #background_table .table {
background-color: transparent !important;
}
</style>
</html>
</panel>
</row>
<row>
<panel>
<table id="background_table">
<search>
<query>|makeresults count=10 | eval value = random()</query>
<earliest>-24h@h</earliest>
<latest>now</latest>
<sampleRatio>1</sampleRatio>
</search>
<option name="count">100</option>
<option name="dataOverlayMode">none</option>
<option name="drilldown">cell</option>
<option name="percentagesRow">false</option>
<option name="rowNumbers">false</option>
<option name="totalsRow">false</option>
<option name="wrap">true</option>
</table>
</panel>
</row>
</dashboard>
