NOTE: Trim the ground header really short on each end if you need to use the power rail headers that interfere. Then after soldering clip those short.

Put the servo header rows into a breadboard upside down, then put the PCB over them (again upside down, the servo headers go on top of the PCB), and shake it a bit to level it all out. Solder one pin on one row, check it's flat, then solder the rest. 

This goes on the bottom.

Install the board with the signal header down into the breadboard and look through the holes over the power rail to see which ones line up. Pull it up, insert 2x1 pin headers in those locations (or location) and then put the PCB back down and solder the other side. 

If you are using a battery pack, solder the screw terminal in place last. You can also power it from a standard RC power connector, solder the power wires directly to the PCB, or use the breadboard power rail.