How to Install Radeon Open Source Driver on Debian Gnu/Linux Distro
GNU/Linux Debian Installing AMD Radeon Open Source Drivers Guide
Hi! The Tutorial shows you Step-by-Step How to Install AMD Radeon and ATI Open Source Graphics and GPU Drivers in Debian GNU/Linux Desktops.
And Open Source Radeon Graphics Drivers for Debian 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.