If you browse the Web with Safari, and open a file that is interesting to you, there is a way of saving this file into GoodReader's internal local storage, so you will be able to view this file with GoodReader without loading it from the Internet every time (like it happens in Safari).
To save a file from Safari to GoodReader:
open the file of interest in Safari
tap Safari's address bar (the keyboard will appear)
go to the very beginning of the file's URL address, where the http:// or https:// part is
add a single letter g in front of the address, so you'll get ghttp:// or ghttps:// instead of http:// or https://
press Go on the keyboard (this will close Safari and start GoodReader)
the file will start to download into GoodReader automatically (check Web Downloads section to find it)