You can prepare your USB stick with NFI Image Flashing for using it
-to repair your dreambox, if necessary /to start the box from the stick, if needed.
If you´re using an older firmware (New dreamboxes are usually sold with older software) on your dreambox, you will have to download and install the "NFI Flash Plugin" onto your dreambox. Then you can use it to format your stick and download a firmware onto it.
If you have a newer firmware on your dreambox (e.g. latest official DMM experimental image) the NFI Flash feature is already implemented in your firmware. You will then find it under "Main Menu/Settings/Softwaremanager/NFI Image Flashing".