Using OnDrawGizmos QUestion

void OnDrawGizmos() {
        Gizmos.DrawIcon(transform.position, "Light Gizmo.tiff");
    }

The second parameter is a string. I assume .tiff is an image of Light Gizmo, but how do i know what directory i am looking in? do I start off at root? or where?

You can place the image in a folder titled 'Gizmos' (which you'll need to create yourself if it doesn't already exist) in the Assets folder. (Be sure to do this in the project view rather than from the desktop.)