First you need to create an anchor that will be the "target".
With Visual Composer, it's very easy to create an anchor.
1. Click the "pen" icon of the row element you want the anchor:
2. Fill the 'ID Name for Navigation' field with the name of the anchor you want. (Eg: about, music or contact). Do not use space or special characters.
3. Add a new menu item in your menu: Go to WP-Admin > Appearance > Menus.
4. Create a new 'Custom Links'. In the 'url' field, add "/#" and your Anchor ID you previously set. So if your anchor is about, the url will be /#about
* If you need to point to an anchor which is on another page than your homepage, then you need to add the slug name in the url. Eg: /bio/#about