1.) Format your MicroSD with SD Formatter 4.0: Raspberry Pi Software Guide
2.) I used Noobs 1.9.2 from here: https://www.raspberrypi.org/downloads/noobs/
Easiest way is to hook up a screen, mouse and keyboard to your RPi 3
3.) Install Raspien Jesse from Noobs.
4.) Open a Command Prompt window. Follow Part A from here: Installing and Updating the Unified firmware
5.) Follow from User Manual : OSPi v1.4+User Manual to assemble and wire your OSPI and RPi 3.
Hope this helps,