Press the green flag. If you are confused why in the pictures from the simulator the rocket looks really small and probably not fit to go to the moon after we discard the other engines and boosters, that's because it's an orbital rocket, not a moon rocket. A moon rocket would do the same thing but have way more parts.
If you are a follower and don't know what this is, it's a school project. You can watch it if you want. I don't know if you'll find it interesting though. Nerd warning for this project. Very technical.