How to write a .iso file to an SD card?
You can use dd to write the image to any drive. First find out what your SD card is called. sudo fdisk -l lists all storage devices. Find you SD card. It should be called something like /dev/sdx where x is any letter. If you have the name make sure it's partitions are not mounted. Then you can copy the image to the device:
sudo dd if=/path/to/isofile.iso of=/dev/sdx
Be aware that the SD card is overwritten entirely.
WARNING
Be absolutely sure you have the right device name. Otherwise you could accidentally overwrite some other device and its data.