It's time to route our tracks.
Autorouting is a method adopted by PCB softwares to make clean connections among footprints terminals: automated process saves much time but cannot be perfect, especially for big project, so that a manual correction is generally required.
Anyway our example will be totally automated.
On top horizontal bar click on penultimate icon (Mode track: autorouting).
Right-click on design to select side for routing tracks.
Here the back one.
A warning will ask if you're sure of your choice, because of matching with bottom layer.
Again, right-click and select "Autoroute -> Autoroute All Modules".
You'll get all tracks as green thick lines: if you had to move them right-click on and choose one among among voices.
An external autorouting system is available for Kicad, called FREERoute (last icon on top horizontal bar).
It requires a Java platform, and lets you save a new file to load into Kicad to get autorouting.
Too much indeed for present goals.