Why does some peoples voice vibrate kinda when they talk is there something to help there voice be smoother or help there voice change?

This change is normal because your hormones are making your voice box change. It will disappear in a few months when your body adjusts to the new levels. What you can do is learn to breathe. Part of the problem is that you are only breathing with the top of your lungs. It's a common problem but can be fixed easily. Find a yoga site and look for breathing exercises. What will happen is that you will learn to breathe with your whole chest and stomach. This way your voice box will have enough air to speak without vibrating. Another plus is that your voice tends to get a bit deeper when you use these exercises. The breathing exercises will relax your voice box which is what the problem is, it gets tight because it's not getting enough oxygen. Congratulations on getting to puberty!!!