Welcome to Linux! Here are a couple sites with command references...
It may seems daunting at first, but generally only need to know a few basic commands to get by.
Type "man" or "info" and then the command for information about its usage.
ls - list files in the current directory
cd - change to the specified directory
cp - copy a file from one location to another
mv - move a file
rm - delete a file
df - information about mounted drives
ifconfig - configure your network devices
route - route your network devices
netstat - displays current connections
vim, vi, pico, joe - text editors
gcc - compiler
make - compiles a project
modprobe - loads a module (driver, etc...), if you want it to stay loaded you'll need to add it to /etc/modules.conf
startx - boots X, most distributions default to a window manager, you can change which with "wmconfig".
tar -xvzf filename is used to decompress a .tar.gz archive or -xvjf for .tar.bz2
Most programs are installed by "./configure" then "make" and "make install" as root. Check the documentation in the "INSTALL" file or whichever is provided.
Use the root account to install software, but for best security, stick to a user account the rest of the time. If you want to switch to root or any user temporarily you can type "su username" and then the password in a terminal.
If you want to create a new user, try adduser or kuser under system in KDE.
Here is a link describing directory structure... http://www.comptechdoc.org/os/linux/...ilestruct.html
Here is a link about setting permissions...
One more link about configuring X Windows....
Fedora Core 3 is a good choice, it's pretty reputable and catered toward user-friendliness.
A couple sites for free open source software are sourceforge.net and freshmeat.net.
I hope this information is relevant, have fun!