What operating system do you have? If you have the white screen it looks like you've managed to get the board into bootloader mode - so then it's just:
Making sure you are connected to the correct (right hand side) USB port
Making sure the drivers are working and the port is appearing in the OS
Figuring out the software you use to flash the firmware
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
What operating system do you have? If you have the white screen it looks like you've managed to get the board into bootloader mode - so then it's just: