1Assemble back side of the pcb
Use the EAGLE design files and BOM to identify which components are which on the pcbs you have ordered from OSH Park. The components on the backside include four 4K7 pullup resistors for the master and slave I2C busses, three 10 K pullups for the reset, interrupt, and I2C select lines, a 100 K resistor for the nCS pullup of, and a 1 uF baypass capacitor for, the W25Q80BLUX1G 1 MByte SPI NOR flash.
You can use a traditional reflow oven or low temperature (Chip Quik) solder paste and a hot plate and air gun to solder the components to the pcb.
2Flash the firmware onto thr SPI NOR Flash
Use a microcontroller with on-board flash or SD card to load the SPI flash of the AS7265X spectrometer with the appropriate firmware (found on the AS7265X github repository).
3Assemble front side of the pcb
Assemble the three AS7265X smart spectral sensors along with one 100 nF and one 10 uF capacitor for each. There are 10 K resistors for spectral sensors 2 and 3. There is a green led (or any color you would like) for an indicator led and the Luxeon LXZ02 5700 K 90 CRI broad-band white led (or any color spectrum you choose) for source.
Use the sketch in the AS7265X repository to verify proper function of the spectrometer and leds.