Add floor and skybox to threejs

gistfile1.txt

// FLOOR
    var floorTexture = new THREE.ImageUtils.loadTexture( 'images/checkerboard.jpg' );
    floorTexture.wrapS = floorTexture.wrapT = THREE.RepeatWrapping;
    floorTexture.repeat.set( 10, 10 );
    var floorMaterial = new THREE.MeshBasicMaterial( { map: floorTexture, side: THREE.DoubleSide } );
    var floorGeometry = new THREE.PlaneGeometry(30, 30, 0, 0);
    var floor = new THREE.Mesh(floorGeometry, floorMaterial);
    floor.position.y = -0.5;
    floor.rotation.x = Math.PI / 2;
    scene.add(floor);

    // SKYBOX/FOG
    var materialArray = [];
    materialArray.push(new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'images/dawnmountain-xpos.png' ) }));
    materialArray.push(new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'images/dawnmountain-xneg.png' ) }));
    materialArray.push(new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'images/dawnmountain-ypos.png' ) }));
    materialArray.push(new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'images/dawnmountain-yneg.png' ) }));
    materialArray.push(new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'images/dawnmountain-zpos.png' ) }));
    materialArray.push(new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'images/dawnmountain-zneg.png' ) }));
    for (var i = 0; i < 6; i++)
        materialArray[i].side = THREE.BackSide;
    var skyboxMaterial = new THREE.MeshFaceMaterial( materialArray );

    var skyboxGeom = new THREE.CubeGeometry( 100, 100, 100, 0, 0, 0 );

    var skybox = new THREE.Mesh( skyboxGeom, skyboxMaterial );
    scene.add( skybox );