For spindle speed control, you are almost there. In addition to hooking up the 12V and 0-10V, you will also need to hook up GND from the VFD control port (port 7) to GND on the BoB (terminal under the 0-10V output). Then you will need to set Parameter Pn 03 on the VFD to 4 (External 0-10V signal).
To have the computer control the on/off of the spindle you will need to hook the relay switched outputs on the BoB to GND and FWD on the VFD control ports (FWD pulled low should be active according to the diagram on page 5 of the VFD manual). The BoB manual doesn't provide much info, but it seems likely that this would be the top right two terminals on the BoB. It would be safest to contact the seller / manufacturer and verify this since the manual isn't clear. You will then need to set Parameter Pn 04 on the VFD to 2 (External signal). Parameter Pn 05 will need to be set to 1 or 3, 2 will not work. Note that this assumes you only want the spindle to clockwise.