I installed Ubuntu Precise 12.04 LTS because Ubuntu Raring 13.04 has a problem with the Gnome desktop.
1. Download Ubuntu OS Image for the BeagleBone
Download Ubuntu OS image from
here 
.
2. Copy the OS Image onto a Micro SD Card
3. Expand The OS File System to Use the Complete SD Card
This steps assumes that there is unused space after the OS image has been copied onto the SD card. The space used by the file system will be expanded to use the complete SD card.
Expanding File System Partition On A microSD