Hi, I am sorry that you could not find how to proceed @F. Helgesen and @SneepyPixels. I am aware of the lack of tutorial (or at least some starting indications). Actually I was in a rush for the submission and did not have time to do this.
But please go to the game page and go to the NOTES section, where I wrote this "A HELP panel needs to be incorporated in pause menu to help people who does not know what to do, such like this ....".