Help me with unity developers

Ok so my problem is i have an AR project where face filters appear on your face, and i know the process and every thing is done except we need a neck binding feature that is present in snapchat i have the snapchat code also and i know the process like what to do but my problems is i’m not so good with c# code in unity and the problem is to bind a rigged model to position and rotation of the world like a root to position and a root to rotation it’s in ar foundation