How to make a smooth scrolling anchor?

Hello,

can somebody help me? i would like to make a smooth scrolling anchor from the canvas and menu link, look like the "back to top" button effect. I have already make the anchor but i just want to make the scroll smooth after click on. Also when i open the sidebar (canvas) and click on the anchor link, it work but after close the sidebar it goes back to top page. How can i resolve these problems ? As you can see the screencapture from localhost the page look.

thanks for help
Rose