thanosxx:
Hello again.As newbie I start with the starter kit and I am reading the book for a general knowledge about arduino and create all project ,then I am thinking go back to start of book and I will try to create simply code (with a led)until understand ,how create a code but for now I have stuck in this project and in this pointint buttons[0]=2;
You might be right. That line seeks to make an array of int variables with zero members and then set it to 2!
Knowledge is power. You need more until your view is clear.
Many links on basic understanding is here:
https://www.arduino.cc/en/Tutorial/Foundations
To get you started with variables:
https://www.arduino.cc/en/Tutorial/Variables
To get you started with functions:
https://www.arduino.cc/en/Reference/FunctionDeclaration
The Arduino Language Reference Page, you might want to keep this open in a browser tab while you use the IDE. It will make checking code quicker and easier. I note the /en/ at the end, there must be versions in not-english.
Good luck. If your head gets tired, take a break right then! It is easy to become fixated on some detail and not see anything else, like answers and then you hit a point where you don't know what's wrong --- from there it is stay and push harder which will burn you out or get away and come back with fresh eyes that see beyond the earlier tight focus.
The human brain grows 'knowledge' in response to stimuli. Sometimes that takes longer than we want.