Remember that small piece of foam left over? Get it out and practice to get the heat setting and feed rate correct. Once you have the temperature set try not to move the adjustment instead unplug or use a switch to turn the power on and off. I use a foot switch, you might find one at Harbor Freight. When the temperature and feed are correct there should be no deflection of the wire visible in the finish cut. There should be no large melt out greater than the wire. You will hear the foam sizzle as the wire passes. You know your temperature is perfect when you observe a smooth cut with hair like foam fibers that are easily brushed off.
When you think you have it set then its time to cut a wing panel. Apply the double sided tape to the templates so that the tape stops just before it gets to the edge. If the wire touches the tape it will snag and if it stops even for a second the foam will melt forming an imperfection in the wing.
Double sided tape in place use the spacer blocks to support the template and line up the leading edge with the line on the template and press to the end of the foam blank. Repeat for the other end and the other template. When you draw the wire through the foam you want the length to enter and exit at the same time. That means the root side will have to move slightly faster than the tip.
I like using weight on top of the core blank to keep it flat and stop it from moving while I am pulling the wire through. When one side is cut simply flip over and cut the second side.
There are lots of videos on youtube.
https://www.youtube.com/watch?v=GWF1XwrgjD4
https://www.youtube.com/watch?v=JfUKWTtpdi8