Install common build tools like gcc
sudo apt-get -y install build-essential
Install dependencies to build the driver
sudo apt-get -y build-dep xserver-xorg-video-ati
Remove current ati driver
sudo apt-get -y purge xserver-xorg-video-ati
Download the newest driver wget
http://ftp.x.org/pub/individual/driv...-6.9.0.tar.bz2
Extract the driver archive
tar xvjf xf86-video-ati-6.9.0.tar.bz 2
Go to the drivers' directory
cd xf86-video-ati/
Configure the drivers'makefiles
./configure --prefix=/usr
Build the driver
make
Install the driver
sudo make install