I'm not overly familiar with Ubuntu, not using it myself, but here goes.
First of all, you should be able to check if you have graphics drivers installed and working by typing
And you'll get a line like
direct rendering: Yes
direct rendering: No
If it's the second one, you haven't installed the drivers, and need to do so.
Once you've downloaded that .run file, you need to execute it, as root (assuming it's in the current directory):
That will guide you through the main installation process for the driver.
When that's complete, you need to run the config tool to update your X configuration:
aticonfig --initial --input=/etc/X11/xorg.conf
Assuming xorg.conf is there of course, which it should be.
Finally, restart X and type fglrxinfo to a command prompt. If all went well, you should see
display: :0.0 screen: 0
OpenGL vendor string: ATI Technologies Inc.
OpenGL renderer string: ATI Radeon 9550 / X1050 Series
OpenGL version string: 2.0.6747 (8.40.4)
and the glxinfo command (above) should return direct rendering: Yes
Hope it helps.