I assume you have basic html skills and you know all about iframes.
Step 1
Insert your iframe code between body tags.
<iframe src="/yourpage.html" name="myframe" width="250" height="250" frameborder="0" allowtransparency="true"></iframe>
Step 2
Now copy the code below, and paste it between <head> tags of the page you are linking to.
In this example this page is yourpage.html
<style type="text/css">
Body { Background: transparent; }
</style>