ImageWriting
This Page is supposed to help you with getting your downloaded .img file to a USB key, either with the usb-imagewriter gui tool or the "old" way in a terminal via commandline.
Using Usb Imagewriter
Click on the download link below to get the usb-imagewriter package. Firefox will offer you to either download the file or, as default action, to open it with the gdebi package installer. Keep the default action here and click ok.
Download usb-imagewriter here
After gdebi finished you will find a new starter in your menu at Applications -> Accessories -> Image Writer
Put the USB Key you want to write the image to into your USB port (give the system a second to recognize it)
Then run the Image Writer tool, select the downloaded image, select the target device and click on "Write to device".
Now just wait until the tool tells you you can remove the key, if you want to see the details of the copying process you can open the details window during operation.
More deatils, screenshots etc. about usb-imagewriter can be found here
If you find any bugs in the tool, please report them here
From commandline with dd
Download the image to your disk.
Open a terminal and plug in your USB key
Run the dmesg command to find the devicename the kernel assigned to it.
In the terminal run:
dd if=/path/to/your/downloaded.img of=/dev/device/you/saw/in/dmesg bs=1024
Wait until your prompt returns, unplug the USB key.