Managing a linux hard drive
I just installed linux and all is well so far but i'm having a tough time getting familiar with linux's file system. I'm trying to download some e-books but i'm out of hd space on my primary partition. Now I have about 3 gigs of unformatted free space that i'd like to use but I don't know the first thing about formatting. I've tried running "fdisk" in terminal but it says invalid command so I really am not sure where to begin resolving this issue. If anybody could direct me to a faq on managing a linux hard drive that'd be great.
Thanks to whoever has the patience to answer