SoRayPickAction in Open Inventor?

Sorry if this is a repeat, but I’m trying to figure out the implementation of SoRayPickAction in Open Inventor. I’m trying to implement it so that it will, when the mouse is clicked, select a particular node so then I can translate, rotate, etc. I have three nodes: desk, lamp, and frame (picture frame). However, I don’t think that my code is at all right. I also have various methods such a MouseButtonCallback (which will check if the mouse is clicked and then use a navigator) and MouseMoveCallback (same idea). So here’s the code that I have, but do you have any suggestions? Right now, well, it doesn’t do anything.

SbViewportRegion viewport(400,300); 
    SoRayPickAction m(viewport); 
    m.setRay(SbVec3f(0.0,0.0,0.0), SbVec3f(0.0,0.0,-1.0));
    const SoPickedPoint *mpp = m.getPickedPoint(); 
    if(mpp != NULL) {
        std::cout << "test" << std::endl;

Might you also know of an action in OpenInventor that can “place” a node in the scene, i.e. place the lamp on top of the desk, frame on the wall, etc. Is it with paths and is the SoRayPickAction also with paths? I don’t even know what I’m looking for, unfortunately. Thanks so much for your help!!