Please help me understand the various ways that textures need to be linked to images I'm having a lot of trouble understanding how Blender handles textures.  It seems to require linking them in multiple places.  Look at the following screenshot:



So here I have a mesh with a cloud texture (texture.002) and a texture in the UV window (untitled.png, saved to disk, which my fumbling suggests matters).  Neither is displaying on my model.  Untitled is not showing up in the texture list.  And texture paint is giving me a warning that there is no texture.  (FWIW, textured display in object mode gives me yet another appearance, which appears to be white.)

I have specific issues-- visualizing my UV mapping, getting a blank texture assigned for AO baking so I stop getting the no object or image error-- but I'm hoping for a more general understanding of these issues.
In order to paint on a texture, the texture must be of type "Image or Movie":