You need to put the tick marks on the lines abov and below the code, and you’ll need to copy and paste it from Godot again to get the tabs back in there, but then I can help you with it. Although it looks like you are using and correctly.
Start with one, and if it gets too big, break it into smaller pieces.
Here’s a couple of posts on the subject that might help. This first one might actually help with your first question:
This one will lead you down a nice rabbit-hole of other links I’ve posted for people. I answer questions like this a lot on here. Let me know if you have more questions after reading.
The fact that you know what you want to build will take you far. The more videos you watch and tutorials you read, the better your vocabulary about programming and making games will be. In turn that will make your questions more targeted, and the answers will get better. Jump in, and have fun!