New to 3D printing, where do I find the settings for....

I printed a spiral vase, and I like that the space in between the walls of the vase are filled with little triangles. I want to know where I "tell" the printer to do that. Is it a CAD/CAM setting or a slicer setting?
I'm doing some 3D printing for my science fair project, and I want to test the strength of various print patterns. Ultimately, I want to change the size of the triangles, and I also want to be able to print hexagons.
I'm new to 3D printing, and I can't figure out where I set this. Help!!

Lisa

All the material between outer walls (perimeters) is called "infill", play with infill settings. To change size of the pattern, you need to change infill density.

Infill settings are found in the slicer application.

@Lisa

Each slicing application (e.g. Slic3r. Skeinforge, Simplify 3D, etc.) has several fill patterns that you can choose from and adjust certain parameters. However, it is not possible to change the predefined geometries.
If you want geometries that do not appear in any slicer, then you have to generate them in a CAD program, as part of the object used for testing.

THank you all. I will work with this!