You can make a nested menu where submenus appear with a click in Webzai using a button group and submenus.
To do this:
1. Add a button group to your page. Uncheck the Enable Button Toggling option in the settings panel if you want the user to be able to have all of the menus hidden if nothing is selected.
2. Add a menu under a button of the button group.
3. Use the manage menu window to have the menu only show the items that you want it to.
4. Repeat for the remaining buttons.
5. Select the 3 menus and make them all hidden in their normal state.
6. Select the first button in the button group and click the Add Behaviour button in the settings panel.
7. Select the show action and click Other Element
8. Select the appropriate menu and click Apply.
9. Set the animation settings as you like but be sure to use Selected as a trigger.
10. Add a Hide behaviour that uses the Unselected trigger to the same button-menu pair.
11. Check that the animation appears how you want it to in preview mode and then repeat this process with the other two button-menu pairs.