I pretty much agree with the lecture titles coming up.
Next steps:
Now that we have mock positions for the enemy ships. It would be nice to have basic collision detection on the player ship. Player collides with anything terrain or enemy it blows up and triggers a restart event.
Then embellish the collision with explosion and sound, to get a satisfying game feel going.
After that, firing at the enemies to trigger an enemy explosion event.
After that, effects to bring the enemy to life instead of just standing there. Basic movement, tweening, make it fire a bullet or two you have to dodge.