Questions regarding rendering of primitives and textures

Hey folks,

I'm not a programmer in a graphics context at all, so my issue might just be me being dense.
My problem is, that i cant get T3D to draw custom stuff like primitives or textures (for stuff like rotated guibitmaps or "radar" stuff).

I guess the way Rendering is handled did chance a lot since TGEA, since stuff that got drawn in TGEA wont draw in T3D. The drawing code gets executed, but i dont see anything being drawn. E.g. did i add this:

int num = 12;
    for(int i = 0; i < num; i++)
    {
        for(int u = 0; u < num; u++)
        {
            for(int v = 0; v < num; v++)
            {
                GFX->getDrawUtil()->drawLine(Point3F(0,0,0), Point3F(i,u,v), ColorI(255,0,255));
            }
        }
    }

inside the onRender() of the gameTSCtrl. No Effect. I expected this to draw primites into the world, like i've seen it with a TGEA resource. Neither did a version with the PrimBuilder::begin() / ::end() yield any results.
Also, i tried to implement this http://www.garagegames.com/community/forums/viewthread/46855 to rotate a GuiBitmapCtrl derivative ... again, without result, even though the code gets executed without errors. The bitmap is either not drawn or the rotation is simply not happening, depending on where i put

GFX->popWorldMatrix();

I'm rather clueless and couldnt find any documentation, howto or resource that would explain this to someone that isnt familiar with graphics related programming. So i hope someone can supply me with a simple howto or just gimme a pointer to where i can look for a tutorial or any sort of explanation on what i need to do and in which context i need to do it to draw something to the screen/into the world.

Big thanks in advance!