To centre your logo so it splits your navigation menu in half, you need to change to a template that supports this feature. An example of this is the “Vista” template with the feature area text “Scenic Helicopter Tours”.
Once your template is changed to a split menu template, you can click “EDIT DESIGN”.
Then click “Logo & Menu” to adjust the spacing either side of the logo. Click and drag the arrows either side of the logo to adjust the spacing.