I am currently working on a website which loads 3d model.I am using THREE.js .In my website i want to upload an 3d model example:Human body skeleton.In that 3d model i want to work on specific group like hand,skull,leg etc.But the problem is i am not able to work on groups of a 3d model,three.js is only rendering the 3d model.

const scene = new THREE.Scene();
const camera = new THREE.PerspectiveCamera( 75, window.innerWidth / window.innerHeight, 0.1, 1000 );

const renderer = new THREE.WebGLRenderer();
renderer.setSize( window.innerWidth, window.innerHeight );
document.body.appendChild( renderer.domElement );