Make sure you are running the public release of Windows 10 (build 14393 or better).
You can find your current build number by clicking the start button, typing "winver", and hitting the Enter key.
To upgrade, visit the Download Windows 10 page.
While Windows 10 is not required to install Windows 10 IoT Core using NOOBS, you'll need Windows 10 in order to use the IoT Core Dashboard app. Windows 10 is also needed to use Visual Studio to develop applications on Windows 10 IoT Core.
To install Windows 10 IoT Core onto your Raspberry Pi using NOOBS you need to have a micro SD Card formatted with NOOBS. You may have received a pre-imaged SD Card with NOOBS already installed. If so, continue to the next step. If you don't already have a NOOBS SD card, we recommend you follow the instructions to install Windows onto a blank SD Card.