How Swing Code Turns Into a Real Graphic Application

This question may not seem very technical, but, out of curiosity, I want to know that:

How does the bare / raw Swing code written by me turn into a great graphics application?

For instance:

• Similar to how we make a JFrame visible or when we place a JButton on it. Who is doing this? OS or Java or JVM.

• Who makes the colors sneak?

• What is the process going on behind the scenes?

I ask about this, perhaps because for the first time in my life I made a graphical application RealWorld, and these questions arose in my head!

Thanks in advance!