Transparency option is placed at Theme Options > Header > Layout.
Transparency is builded from three different options, as usual the first one stands for default or the classic one.
When sticky is activated at the moment you pass the header section and you scroll up the header will be displayed, only then, when scrolling down the header wont be visible, for the reason to not interrupt the user reading the content.
Auto Hide – Switch on if you want to activate the autohide header. The header will be hidden when scrolling down, it will appear only when user scrolls up.