Help needed with my first game ever!!!

Hi, i would like to apologize upfront for my poor English as it is my second language. With that said, i am a beginner game dev trying to make a game to propose to someone but the only problem i have is that i am absolutely new to development and don't really understand the engine i am using which is Unity.

I watched tutorials by Jimmy Vegas on the engine.

Now the concept is simple, i wanna make that special someone the main character and as she plays guitar, i would like to make that as her weapon. My character would take her to outer space and there she gets to fight the alien that is the enemy. I put in a Guitar Amplifier in as the ground you stand on and thought of pressing keys would shoot out lasers through the amp. but how do i do that? how to set it up?

i was told to take a cylinder, put a neon skin over it and give it a forward velocity, but i was also told about the particle system.

I've set up the first person controller, imported the amp and gave it a box collider and also imported the guitar and attached it to the player.

what do i do next to add in the laser?

also, Any suggestion will be appreciated!!