Since each Pneuduino valve board has its own microcontroller, you have the option to not connect it to the main board, if you only want to use only one valve board. To do so, you will need a 6 pin (one row) pogo pin, and a USB-FTDI cable/board to program it directly.
1. The contacting area is on the bottom of the valve board (if necessary).. You can see five circular and one square copper surface areas there. The square represents GND, so you can orient your FTDI correctly.
2. Install the USB-FTDI driver in your computer (if necessary). Connect your USB-FTDI cable/board to your computer. Then plug the pogo pin into the female header of the cable/board.
3. Now press the pogo pin exactly on the contact area of the board. Make sure that you chose the board Arduino Pro/Pro Mini. Then you can go ahead upload the code.
4. If you got errors, try to reverse the orientation of your pogo pin. please make sure that the pogo pin is in good contact with the copper area. And make sure that your FTDI cable/board works properly.