Can't run libGDX, Excluded, how to fix error?

Question

Java

I want to write programs, just so that you can do whatever you want and write games.
in javafx, it seemed to me that only templates can work and you can’t put something of your own.
if someone can teach how to write programs, help me start becoming a good programmer, write a program, and explain the essence, write to [email protected]
I import the libgdx project via build.gradle, everything seems to work, I launch Aplication and everything is red, libgdx starts then disappears and everything is in Excluded errors. I add to the exception shows two errors.
Error:(5, 22) java: cannot find symbol
symbol: class MyGdxGame
location: package com.mygdx.game
Error:(10, 42) java: cannot find symbol
symbol: class MyGdxGame
location: class com.mygdx.game.desktop.DesktopLauncher