I just installed Ubuntu. I am new to Linux, so I will need this explained in pretty basic terms please. I have two monitors. I use a AMD R7 2xx graphics card. I haven't installed the AMD drivers but don't know if I need to or not. In terminal I used the command xrandr --addmode DVI-0 1600x900 to add that resolution to my second monitor. It works fine until I restart the computer. I read something about needing to change a xorg file in /etc/X11, but that directory doesn't exist on my computer. Not sure what to do.