1. Open XenCenter , Create New VM And Select Centos 6.4

2. Click Next and give name to your new VM

3. Click Next Select Install from url and enter installation url.
For 32 Bit
http://mirrors.sonic.net/centos/6/os/i386/
for 64 Bit
http://mirrors.sonic.net/centos/6/os/x86_64/

4. Select which xenserver you want to install if you have more than one.

5. Select CPU and Memory

6. Change Storage Size if you want.

7. Select Networking option and click next.

8. Click Create Now and start installation.

9. After VM Started Select Language

10. Configure Network and Click OK.

11. In next windows you can select text based or vnc based installation. It is your choice I prefer to start VNC

12. Enter VNC Password two times and select ok.

13. Please not your ip address and port for connecting vnc. Start VNC client enter you ip and port and click connect.

14. After VNC Connected Click Next and Start Installation

15. Select Your Language and Click Next

16. Select Storage options

Discard any data

17. Select your hostname.

18. Select your timeframe.

19. Enter your root Password

20. Select Replace Existing Linux

Write Changes to disk.

21. Select Packages you want to install.

22. After installation done click reboot to start vm

23. After System Restarted Login with your root password and insert Xentools iso to Virtual DVD Drive.

24. use those command and install XenTools.
mount /dev/cdrom /media
cd /media/Linux/
rpm -i xe-guest-utilities-xenstore-6.2.0-1120.i386.rpm
rpm -i xe-guest-utilities-6.2.0-1120.i386.rpm
note : if you installed 64 bit version you need to install 64 bit tools.
reboot and ready to go.