In your dashboard area go to Appearance->Theme Options, and choose the "Custom Style" tab. You will need to add CSS in the Custom CSS editor here.
I can't for the life of me figure out how to reduce the spacing between the slider and navigation...
You'll need the following CSS:
You can change the value of
padding-bottom as you wish, depending on how much space you want between the slider and the navigation.
...and the title and body of my pages
Try the following: