Here is a quick and simple jig for soldering your LEDs to your LED board. All you need is a couple short lengths of 2x6 and some hardware you can easily find at your local hardware store...

Cut a 6 inch long piece of 2x6, place one of your LED boards on it and transfer the three pre-cut holes onto the board.  Drill holes all the way through the board to take some 8x32 screws. Now put some long (3 inches or longer) 8x32 screws through the holes. Cut another 6 inch piece of 2x6 and put it on the back side of the first and screw them together with deck screws holding the 8x32s in place.  Use the nylon bushings and washer you got in your kit and make some standoffs as seen in the photos below (click for larger images).  Make sure you make the standoffs high enough to allow you enough LED sticking out the front of the board to make the bends specified in the instructions...

Next, place all of the LEDs in your LED board (make sure you orient them properly) and then place the board on the jig.  Actually, it is easier to place the jig on the board so the LEDs do not fall out.  Use some compression springs and nuts to hold the board down against the standoffs and hold the assembly together...

Before you start soldering make sure the LED board is all the way down against the standoffs and that the LEDs are all the way down against the 2x6 and are straight...

Hope this helps.....and have fun!!