Trying to use amd fglrx driver, unity does not work ubuntu 12.10

I just installed Ubuntu on my Samsung series 3 laptop (NP305E7A-A02US) with an AMD A6-3420M with Radeon HD 6520g graphics, and I am trying to install the flgrx experimental driver. However, I can not find the experimental driver, and when I use the stable version of that driver, the top bar does not show and the Unity launcher does not show up. On top of that, when I try to install the AMD drivers from the AMD site, it gives me the error One or more tools required for installation cannot be found on the system. Install the required tools before installing the fglrx driver. Optionally, run the installer with the --force option to install without the tools. Forcing install will disable AMD hardware acceleration and may make your system unstable. Not recommended. See /usr/share/ati/fglrx-install.log for more details. I checked the directory and sure enough, it said Supported adapter detected.
Check if system has the tools required for installation.
fglrx installation requires that the system have kernel headers. /lib/modules/3.5.0-20-generic/build/include/linux/version.h cannot be found on this system.
One or more tools required for installation cannot be found on the system. Install the required tools before installing the fglrx driver.
Optionally, run the installer with --force option to install without the tools.
Forcing install will disable AMD hardware acceleration and may make your system unstable. Not recommended. I have no idea what this is and I need to fix it, as I was accepted into the Steam for Linux beta, and they recommended this amd driver. Any help is greatly appreciated. Thanks so much!