To install a particular OS image

Second we wll see to install a particular Operating System Image,

1.     Download Official images for recommended Operating System Eg - Raspbian.

2.    unzip it to get the image file (.img) for writing to your SD card.

3.     We need to use an image writing tool to install it on your SD card.

4.    So download the "win32 disk imager".

5.     Insert the SD card into the laptop/pc and run the image writer. Once open, browse and select the downloaded Raspbian image file. Select the correct device, that is the drive representing the SD card.

6.     click on the "Write" button.

7.     Once the write is complete, eject the SD card and insert it into the Raspberry Pi and turn it on.
8. Setting up the Pi            

                 after booting the Pi, there will be asked for username and password. So use default username and password.
When the Pi has been booted for the first time, a configuration screen "Setup Options" will appear. 

If you didn’t get "Setup Options" screen, then type "sudo raspi-config".

• Select the first option ( "Expand Filesystem") in the list of the setup options window, and hit the enter key. We do this to make use of all the space present on the SD card as a full partition. All this does is, expand the OS to fit the whole space on the SD card which can then be used as the storage memory for the Pi.

• Select the third option ("Enable Boot To Desktop/Scratch") in the list of the setup options window and hit the enter key. It will take to "choose boot option" window.
  
  In the "choose boot option window" , select the second option( "Desktop Log in as user 'pi' at the graphical desktop") and hit the enter button. We do this because we want to boot into the desktop environment which we are familiar with. If we don't do this step then the Raspberry Pi boots into a terminal each time with no GUI options.  

•  Select the "finish" button and it should reboot automatically. If it is not type “sudo reboot”  

 9.   Updating firmware

       After the previous step, if everything went right, then you will end up on the desktop which looks like below image.

Then open a terminal and enter “sudo rpi-update” command to update the firmware of the Pi.