I am trying to create a button that when you click on it it will create a pop up. This is my button Click on

I am trying to create a button that when you click on it it will create a pop up. This is my button

document.getElementById("button").addEventListener("onclick",()=>{

alert("Hello");

})

This is not working. what am i doing wrong?

and how do i create the pop up button? im not sure how. thank you