Sorry, I thought you needed an intro to charting.
You want to use column 3's data to change the colour of points plotted from
column 2?
That would take some fancy VBA ; may I suggest you post the question in the
Excel.Programming newsgroup?
It would help if you included some sample data (especially the values in the
third column)
But on Jon's site you will find how to make conditional charts - different
coloured point for different value ranges