Installing the system on your SD Card
1. Download the system software here:
http://www.raspberrypi.org/downloads – choose the latest Raspian “Wheezy” installer
Once the file downloads, extract the image by double clicking on the download file and put the image file on your desktop.
2. Insert your SD card into the card reader and see that it mounts on the desktop
3. Open the OS X Disk Utility application from your Utilities folder.
4. Select the SD card partition in the left-hand menu and click on the erase tab.
5. Make sure the format is MS-DOS(FAT) and click on erase to reformat the card.
6. Once the card formats choose ‘verify disk’ and look for the BSD name: must be something like diskn where n is a number (for example, disk4). Note this number.
7. Click Unmount from the menu above.
8. Open the Terminal application from your Utilities folder and run the following:
sudo dd if=path_of_your_image.img of=/dev/diskn bs=1m
Make sure to replace the ‘n’ of ‘diskn’ in the command with the number you noted from the BSD name in the previous step.
here’s what the command looked like on my computer
sudo dd if=/users/dwingus/desktop/2014-01-07-wheezy-raspbian.img of=/dev/disk3 bs=1m
This step copies the Linux system software onto the card. Once you hit return to start the 'dd' command your terminal will look like nothing is happening at all. This is a good thing. Go get some coffee and relax. An eight gigabyte SD card takes around fifteen minutes or so to format properly. Larger SD cards will take longer.
When the card is formatted you will see something like the following on your terminal:
2805+0 records in
2805+0 records out
2962227200 bytes transfered in 1002.34582 secs
Drag the icon for your SD card to the trash and remove it from your laptop.
Insert the SD card into the Raspberry Pi and plug it in. Have fun!