Moving Site

I know this has been asked a million times, but I want to make sure I understand.

On the same server and domain I created a new wordpress instance in a different directory for example. my original site was xyz.com and i have redesign my site in xyz.com/newdesign. Now I want to move my new installation into the xyz.com directory. Couple of things, I am using the same template and a lot of the same photos so I didn’t want to just copy over content without fully understanding. Anyone done anything similar? Thanks