A little note. When you use the find command it will not examine files and folders you don't have permission to play with. To get around that use "sudo find / -name <filename> -ls"
The "-ls" after the file name will give you a listing for the found file(s) the same as if you used "ls -dils" in a terminal with the file in it and shows you much more information including the full path to the file.

Find is a very useful and powerful command if you get right into it. "man find" will keep most people busy reading about it. Learning it fully will take much longer.