On the lcd, double tap the screen where you want to zoom and it will activate, then use the top and side wheels to zoom in and out. Also, you can remap your function buttons to activate it as well. I have in on F3.
I believe F3 is the factory assignment for expanded focus. I was unaware of the double tap on screen activation..seems that would get you to desired focal point faster.
To enter manual focus push the Focus Mode lever around the AF/AE Lock button to MF.
To move the active MF area Press Fn3. This brings up the manual focus rectangle with bounding arrows in a box within a box display. Note MF uses a rectangle, AF uses a square so you can tell at a glance which focus function is active.
Move active MF area with the Control Dial. Recenter by pressing Disp. The MF area can be set anywhere in a box about 3/4 the linear size of the whole frame.
To change the size of the MF area use the rear dial for big steps and/or the front dial for small steps.