Open menu:

Click this icon     in the upper left corner of  the screen. The Menu appears. The screen is darkened.

Close menu:

Click anywhere outside of the menu or click this icon    in the upper left corner of  the screen. The menu disappears. The screen will light up again.

If You see the green arrow on the Menu item it means  there is a submenu with more content  on this menu item.  Click the Menu item to read more.