I have started learning about editing photos , I want to edit photos for printing only. Therefore I need to know about resizing , howerver, I have spent weeks , reading and watching videos about this , and they all speak the same editing language without being specifically about what is needed, I mean the rules to follow etc and process that is involved. For example,of this, resolution and pixel ,dots per inch,they all mention of the name of them, and mention "put photos in a number of of 200 ppi," without given any detailed explanation about why this is so!, when there are so many other numbers from the same catergory. In order to resize a photo there is needs to be more specific information that is needed about it when photo editing is involved, 'custom' resize photos. So if someone could assist me with this. From a tutorial,and specific,level, I can start rezising my old photos. Thanks. 
