Help me with an Idiots Guide to Solving the Black Screen?

Imagine my sadness when "sudo startxfce4" launched only a black screen. Unfortunately I am a complete linux idiot. A HUUUUGE part of my Chromebook usage was VLC in Linux. Can anyone help? I have an Acer Chromebook 14 and miss Crouton. These are the instructions I've gathered so far:

#1. Install crouton, the "trusty" version of linux, and xfce4/unity/kde. My favorite guide for this whole process:

http://davebennett.tech/install-ubuntu-14-04-on-chromebook/

#2. Do the typical Ctrl-Alt-T, write "shell", hit Enter, and then type the following:

    sudo sh ~/Downloads/crouton -u -n trusty -t xiwi

#3. Somehow replace ???? with ????. Can someone help me with some idiot-proof instructions on how to do this?

Section "Device"                                                                                                                                     
#   Identifier "Intel Graphics SNA+TearFree"                                                                         
#   Option     "AccelMethod" "sna"                                                                                                                   
#   Option     "TearFree"    "true"                                                                                                        
   Identifier "Modesetting"                                                                                                                
   Driver     "modesetting"
   Option "AccelMethod" "sna"
   Option "TearFree" "true"                                                                                                                  
EndSection 

#4. (Not so sure about this one) Every time I use Crouton I need to enter the following to launch Linux:

sudo startxfce4 -X xiwi