[Plugin: Polylang] Problems with menu, titles and contents

Hello!
I’m newto wordpress and codex and plugins etc. I’m creating my website with pique theme and this is what I have done.

I need to make an Italian version of the website.

I’m having trouble because:
1. When I switch to the Italian version the main menu disappears.
I’ve read about “wp_nav_menu” but I cannot understand where to change the code. Is in “wp_nav_menu” the solution ore somewhere else?

This is what i see in the header:

wp_nav_menu( array(
						'theme_location'  => 'primary',
						'menu_id'         => 'primary-menu',
						'fallback_cb'     => 'wp_page_menu',
						'items_wrap'      => '<ul id="%1$s" class="%2$s">%3$s</ul>',
						'walker'          => new Pique_Menu(),

2. Titles of all sections are still in English. Only contents of “services” section (child pages of parent page “Services”) are in Italian. Everything else doesn’t change.

Where should I have to start to solve my problems?

Thank you