Secure the wire leading from the inverter down the tongue of the shoe in the same manner as you did the wire from the EL panel. Plug the cables together and tuck the junction between the laces and check for a comfortable fit.
A 1.5" circle of EL panel is about as much as this tiny coincell inverter can power at once, and the battery life is about an hour before noticeable dimming. You can increase battery life by upgrading to the 1xAAA inverter (which is only marginally bigger but a little heavier) or try making cutouts where the EL panel is not used (less panel = longer glowing).