This template was based on Helix3 framework it means that allows you to use Off Canvas Menu [=] for Small Tablet and Smartphone views. It doesn't have to be Main Menu, it means that you can easily use different menu for desktop and  separate menu for Mobile & tablet devices. To create such a menu Add/Edit a Menu module and change its position to "offcanvas", select Menu from the list and assign module to all pages. 

To add search or other module inside offcanvas menu window, you have to publish those additional module(s) in "offcanvas" position and then choose their order relative to each other.