Child theme PHP question
				
				
                
                    
                    
                
                
                    
						
                
                
                    Hi Guys
At the moment, I’ve modified core php files.  So I’m now at the stage where I want a child theme, instead of messing about with core stuff,  because soon I will install 1.7 (which will over-write the core modifications)
I’ve read the tutorial, but it only mentions about CSS.  I don’t understand how the child theme works for php files? 
Do I literally just copy over any core php file I want to modify e.g. footer, wrapper, and simply just drop it into the child theme? (and modify it)  Is it that simple? 

  or do I need to know anything else?