RaspberryPi web store. I also bought some accessories, USB hub, Wifi dongle, and HDMI cable from local store.
I followed as in the installation manual to setup the rPi as media centre. I chose to use XBMC. It was installed successfully with no major problem. I plugged it to my TV. I also use iPad to control it using Official XBMC remote/IOS.
It works perfectly. Now I am exploring my new XBMC.