Install it so it can run on your machine????
The source code was given so you could learn. The very first line of the do_fill() module is:
Code:
module do_fill() {
translate([-7,-14,0]) import("fibofidget.stl");
That is how original image gets pulled into OpenScad to be modified.
To proceed, you would make a source file called do_fill.scad in some directory. Put that code into the file do_fill.scad. Put the original .STL file (with the correct name of fibofidget.stl) in the same directory. Double click on the do_fill.scad file from within Windows Explorer. That will bring up OpenScad. You should see an initial rendering of the output at that point.