Installing Raspbian OS

The minimum size for Raspbian OS is 4GB and is generally downloaded from http://www.raspberrypi.org/downloads/ before being installed to an SD card.

Windows

In order to prepare the SD card for installation from a Windows platform, download the following software http://fedoraproject.org/wiki/Fedora_ARM_Installer#Windows_Vista_.26_7.

1. Extract the files to a folder of your choice
2. Eject any devices or storage media
3. Insert your chosen media
4. Right click fedora-arm-installer.exe and select Run as Administrator
5. Select your source image (downloaded from raspberypi)
6. Select destination (ensuring it is correct as it will format it)
7. Click Install (this may take a while)

Mac

A shell script is available to prepare the SD card from https://github.com/RayViljoen/Raspberry-PI-SD-Installer-OS-X

1. Extract the files to a folder called Raspberry-PI-SD-Installer-OS-X-master
2. Move the image file downloaded from raspberrypi to the folder specified in point 1.
3. Open Terminal type cd and the full folder path of Raspberry-PI-SD-Installer-OS-X-master
4. Eject any devices or storage media
5. Type sudo ./install *name of file*.img and enter the Mac password
6. Enter the number relating to the installation device

Your SD card should now be ready for running of setup here

Reference:

https://learn.adafruit.com/adafruit-raspberry-pi-lesson-1-preparing-and-sd-card-for-your-raspberry-pi