Add another div, above the iframe's div.
Put the image in that div. You can add any styles you need to position this div the way you want.
Add the style clear:both; to the div containing the iframe.
You should really have a div around ALL your content and set styles for that which defines its width, margins, padding, fonts etc.. Often you will see this div with the class or id of wrapper or main or content.
It would be better if you learned to use a css file, put all your styles in that file in the head, and give each of the divs a class to apply those styles. Currently, your page is extremely basic and is ignoring all normal design guidelines.
Currently, you are just styling the body, which will apply the styles to the rest of the page', but each div should have its own styles in a class, and the class used as often as needed.