I just installed Xorg on Arch Linux but when I run startx, I only get a blank screen. What could be the problem here?
This is actually normal if you do not have a
xinitrc with a command to start a window manager (or any GUI app). You can also tell startx what it should run directly from the command line:
startx `which xterm`
will start an Xorg session with an xterm window. you can run stuff from it if you want :) But better install and use a window manager.