Managing alert sounds with the new update

Hi friends, I am so excited to read about the ability to silence some notifications (text messages) and not others (phone calls) with the new update. That has been my number 1 issue with the MK since I got it but I love the phone so much I have just been patiently waiting. BUT–I read this is now possible with the new update yet I cannot find where I can do this in settings. I am sure there are instructions somewhere but I have missed them. And I cannot find how to do it myself. Help please!