Instead of LoadLevel, how do i use SceneManager - unity3d

Question

I super new in coding and I couldn't find the right answer on the web. All I want is just change scene in my game. I've already had the buttons etc. But i can't choose the "menu" script from the On click function menus.
All answer is welcome!
using UnityEngine;
using UnityEngine.SceneManagement;
using System.Collections;
public class Menu : MonoBehaviour {
public void ChangeScene(string sceneName)
{
SceneManager.LoadScene("sceneName");
}
}

Answer 1

Several problems here. First, the function "ChangeScene"
public void ChangeScene(string sceneName)
{
SceneManager.LoadScene(sceneName);
}
Then, you may have a problem in your scripts since you can't add any listener to the OnClick delegate. Fix every problem thrown by the console. A strange thing is that the name of the Menu script does not appear in the Menu component. Make sure the filename is "Menu.cs"
Finally, drag & drop the button into the field under "Runtime Only" and select "Menu > ChangeScene"

Answer 2

You can't just plug in the Menu script to the left slot.
You have to attache Menu to a GameObject then plug that GameObject to the left slot.You will then be able to chose which script and function to send the event to on the right.
The Image below shows the wrong way to do this(This is how you are currently doing it):
The is the correct way to do it:
You can also do this from code:
public class Menu : MonoBehaviour
{
public Button playButton;
void Start()
{
//Add Button Event
playButton.onClick.AddListener(() => buttonCallBack(playButton));
}
public void ChangeScene(string sceneName)
{
SceneManager.LoadScene("sceneName");
}
private void buttonCallBack(Button buttonPressed)
{
if (buttonPressed == playButton)
{
ChangeScene("myscene");
}
}
}