Asking about command

Hi guys, I'm starting learn Linux, if i want to check all files system and my private file in Linux, which command can help me? also if I would like to add word file in Linux and would like to write something in it or file to put pictures how I can do it using Linux command? the last question if I have backup inside the server and would like to know how to enter the backup file to check every file and folder inside it and than run this backup which command I need to use? thanks