How do I link Unity game objects into my C# code?

Hi
I'd like to link my Unity game objects into my C# code
My Unity game is ready to have the c# game-state in my singleton link in its corresponding game-state data structures to existing objects in the Unity IDE.



What does it look like to set up an array of Unity objects in the script? and instantiate them? Should I tend towards using already existing objects?

I need:  an array of clue-images, an array of text objects (TextMeshPro) and an array of (basically) platforms
?

Thanks