Hi Ger,
I recommend this
html slideshow script
It uses jQuery which is a javascript library which you'll also have to include in your page code. This can add an extra overhead to your page load time and compiled page size.
Its easy for me to use as I always use jQuery with all my projects, but you'll have to decide for yourself whether using jQuery is the way you want to go.
You metioned that you are not very good with js, so maybe this may be a bit over the top for you, but once you go jquery, you'll never look back!
You can also build a custom jquery library by choosing only the bare minimum components you need. For more info check out
jQuery: The Write Less, Do More, JavaScript Library