GNU/Linux Ubuntu Installing AMD Radeon Open Source Drivers Guide
You Are Welcome! The Tutorial Shows You Step-by-Step How-to Install AMD Radeon and ATI Open Source Display Drivers in Ubuntu GNU/Linux Desktops.
And Open Source Radeon Graphics Drivers for Ubuntu includes Updated Free Graphics Drivers for AMD Graphics Cards.
Especially relevant: as a complement you may be intesested also to the MESA Graphics Drivers Suite Setup.