More than likely GRUB is set up to boot in run level 3 instead of 5. When you did the install, if it didn't prompt you to create your user accounts, it wouldn't be able to launch with a GUI as root is all command line unless preconfigured otherwise. once you log in as root, to check to make sure that x is installed correctly try running "telinit 5". That'll force it to change to run level 5, which is multiuser graphical and will load x conf files. beyond that you'll have to manually add user accounts and specify that it loads scripts from rd.5 in your bootloader.
Also, if you're just getting started with linux, take a look at
www.ss64.com It contains the man pages for most of linux's bash commands and is very useful when you're not sure how to do something or just need reference material.