How do I install drivers for Radeon HD 7550M/7570M/7650M in Ubuntu 14.04?

I want to play some games. For that, I need to update my drivers.

I have run this code:

    david@David-Laptop:~$ lspci -vnn | grep -i VGA -A 12
00:02.0 VGA compatible controller [0300]: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0126] (rev 09) (prog-if 00 [VGA controller])
    Subsystem: Hewlett-Packard Company Device [103c:17f4]
    Flags: bus master, fast devsel, latency 0, IRQ 48
    Memory at d0000000 (64-bit, non-prefetchable) [size=4M]
    Memory at c0000000 (64-bit, prefetchable) [size=256M]
    I/O ports at 4000 [size=64]
    Expansion ROM at <unassigned> [disabled]
    Capabilities: <access denied>
    Kernel driver in use: i915

00:14.0 USB controller [0c03]: Intel Corporation 7 Series/C210 Series Chipset Family USB xHCI Host Controller [8086:1e31] (rev 04) (prog-if 30 [XHCI])
    Subsystem: Hewlett-Packard Company Device [103c:17f6]
    Flags: bus master, medium devsel, latency 0, IRQ 45
--
01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Thames [Radeon HD 7550M/7570M/7650M] [1002:6841] (rev ff) (prog-if ff)
    !!! Unknown header type 7f
    Kernel driver in use: radeon

03:00.0 System peripheral [0880]: JMicron Technology Corp. SD/MMC Host Controller [197b:2392] (rev 30)
    Subsystem: Hewlett-Packard Company Device [103c:17f6]
    Flags: bus master, fast devsel, latency 0, IRQ 18
    Memory at d0703000 (32-bit, non-prefetchable) [size=256]
    Expansion ROM at d0710000 [disabled] [size=64K]
    Capabilities: <access denied>
    Kernel driver in use: sdhci-pci

03:00.2 SD Host controller [0805]: JMicron Technology Corp. Standard SD Host Controller [197b:2391] (rev 30) (prog-if 01)

Install the driver by running in terminal

sudo apt-get install fglrx-updates

Or you can do the same in GUI.

System Settings -> Software & Updates -> Additional Drivers.