Modifying the single.php file to make post date more prominant

Hi,

At the moment our single posts (eg. https://blueventures.org/new-research-bright-spots-shine-light-future-coral-reefs/) show the main image and then the date and tags etc. I'd like to move the date only above, or ideally overlayed over the top of, the featured image. I can work out the css to make it more prominent but don't know where in the single.php to make this change. That code is here: http://pastebin.com/VqQjyykS

Many thanks!

Martin