Ati proprietary driver not working I have switchable graphics and on installing ati drver it ends up in blank screen after startx

Sir initially BT5 was not starting on my pc...
On writing startx on command log it used to directly take me to a blank screen with nothing to do...
On searching a lot on forum I tried the kernel command (xforcevesa noapic noapci nosplash irqpoll) it somehow forcefully started BT5 but it was lagging as I found no graphics card on BT5 and it was not able to give 3d acceleration...
I tried to install graphics card by having the application jockey-gtk but it said install archive () failed
I further tried it getting drectly getting from website by typing command...
wget http://www2.ati.com/drivers/linux/ati-drivers/linux/ati-driver-installer-11-5x86.x86_64.run
sh ati-driver-installer-11-5-x86.x86_64.run
It installed correctly but on booting it again gave me the blackscreen issue which I was facing before...probably due to something wrong in driver installation...
Can you please tell me the correct way to install driver for ATI 5650 HD radeon