The OP says: "How do I point a selected camera"...
The keyboard shortcut given in the accepted answer will move the 'active' camera, which is not necessarily the selected camera. A 'selected' camera and an 'active' camera can be two different cameras, if there is more than one camera in a scene.
A full explanation of how to make the selected camera into the active camera is here, for anyone on the same mission I was on: How can I make a camera the active one?
I'd set my view up first and had a tough time with all these keyboard shortcuts so for anyone new like me grappling with more than one camera in their scene.
UPDATED from comment below (Thanks Mr Zak):
- Navigate by panning/zooming/rotating your 3D view to what you want.
- Select camera (if not already selected)
- ctl + Numpad 0 make selected camera active
- Numpad 0 Return to desired view
- ctl + alt + numpad 0 Align the camera to view.
It's actually a really neat set of shortcuts. Blender rocks!
I found that aligning an added camera to the view I'd created did not give me a result I expected. So I currently find it easier to select the (active) camera and move it using G + X/Y/Z or G + XX/YY/ZZ. There are answers above about setting up the camera to track to an empty and answers elsewhere about sorting the camera out, but this is a quick-n-dirty render I'm doing.
(I originally intended to add a short explanation that the selected and active cameras can be two different things just to give the inexperienced, like me, a 'heads-up' in the comments on the accepted answer, where it would be most useful - except I need 50 reputation points to do so and only have 35 at time of writing).