Want to "pimp"/modify an indicator

Hello,

I need help to modify an indicator for mt4. Do not know what the real name is, but it is a histogram that shows + volume above the zero line and - volume below the zero line. The way it looks now is only 1 color, but I would like it to change color to green when the histogram bars goes above zero, and red when below, or better yet: make the colours customizeble. Also I like the bare thikness to change when direction change. See picture to see what I mean: 

(Indcator on top has the kind of histogram I want, indicator on the buttom (blue bars) is the indicator I want to modify)

I imagine this is a pretty simple job for somebody familiar with indicator programing since it is only a visual change.
NO programming of indicator code, only how it plots on the historygram.

This indicator is for my personal use only.