By default theme displays its standard logo in header. You can replace it with your logo image. Go to Theme Settings > Menu > Logo Settings there are 2 options for logo. First one is general logo and retina logo. Click “Upload” button and select logo image from your computer then click “Insert To Post”
You can also adjust logo margin top/bottom value using Theme Setting > Header > Logo Margin Bottom and Logo Margin Top too.
Fullscreen Templates Logo
On some fullscreen templates ex. fullscreen slideshow. Main menu bar & logo will be reduced height in order to provide more screen space for fullscreen content. So you can change maximum logo height, margin values in Theme Settings > Menu > Fullscreen Templates Logo Settings