In my node setup I need to add an image and an alpha over (circled) to my current node setup so the logo sits on top. I’ve tried a number of different ways but when I render the logo is not visible on top. Can someone please tell me how to do this?
You’ve connected the logo to the wrong input. Anything that’s supposed to be composited “on top” must be connected to the lower input. Backgrounds go “on top” and foregrounds “below”. 
Blender nodes are weird. bottom socket = on top
It’s perfectly understandable why this confuses novice compositor users and I think it’s about time that more natural mappings are used. I know Blender always tries to be different but this might not always make sense and complicates issues without reason.
Thanks Daccy. So I moved the input to the bottom, thanks for that. What I was also wanting to know is the nodes (circled in red) need to connect to the nodes above them don’t they? How do I connect the bottom nodes to the top ones?
At first I also thought it’s weird that you have to connect images to inputs this way.
This confusion comes from habits that I had from using layer systems where you indeed place images “one over another”.
Here I simply had to re-define my way of thinking:
You don’t lay one image on top of the other, but connect “first” image and connect “second” image. Node performs operations on them.
If we think about the “flow” of our noodle - blender’s way of connecting to nodes seems very logical:
The flow is from left to right and top to bottom.
If we were to connect “second” image to upper socket, out connecting lines would cross one another too often.
When I begun not to say: “Lay one image on top of the other”, but instead I say: “First input and second input” - Blender’s way started to be obvious.
@Bartek: the apparent contradiction comes from the fact that the “base” image goes to the “top” socket instead of the bottom one.
Like I said, a more natural, everyday-world mapping would be the exact opposite. After all when you refer to the book on the top shelf of a two-self bookcase you really denote the one higher up, don’t you?
@Bartek: the apparent contradiction comes from the fact that the “base” image goes to the “top” socket instead of the bottom one.
The current method makes it consistent with the other areas of blender where order is important, Top to bottom is the order in which things are added.
So I moved the input to the bottom, thanks for that. What I was also wanting to know is the nodes (circled in red) need to connect to the nodes above them don’t they? How do I connect the bottom nodes to the top ones?
Can someone please help me with the problem. 
An alpha-over node acts like a mix node. Connect the output of the color balance node (your corrected background image) to the top “image” socket of the alpha over; your logo image goes into the bottom socket of the alpha over. The output of the alpha-over node goes to the final composite node.
Far as I can tell, the Image output from the Color Balance node should be the first (top) input for the Alpha Over node, and your logo image (can’t say why it has no image in the node preview) should be the second (bottom) input to Alpha Over. Image output from Alpha Over should go to Composite and, optionally, to a Viewer node.
Thanks CD38 and chipmasque. Worked well.