Creating an overlapping chart

[jaywizz]

I have attached a spreadsheet as an example.

I have attached the images
Image "Overlap" shows an overlaped chart (which I want to be able to do)
Image "12" shows a line runningn along the peak of each bar (also want to do this).

The Problem
I have temprature 2 readings for each day. I want to show that information in a chart but I'm having a couple of problems.

1. I want the two readings for each day to be overlapped (shown behind one behind the other)

2. I would like to have a line tracking the high point of each of the high temps and the same for each of the low temps.