2D and 3D images

How do you display 2D as well as 3D images on a window.

I am trying to create a very basic first person shooter. I have my 3D object (which on its own displays fine) and I want to create a crosshair (static 2D image) in the middle of my screen. Any help would be greatly appreciated.

Take a look here:


OrthoView is that you are looking for.