How to create score counting text in the latest version of unity? I have tried placing unityengine.ui and it gives me error. I will acknowledge the help

The unityengine.ui library does not work for me and it gives me an error.

Please ensure that you are using the using UnityEngine.UI
with a uppercase U and I.
also for the score it would be an int that would increase++ when something specific happens
let’s say I want int ‘i’ to increase on a button click I would put it as

public static int I;
public Bool PlayerHasEarnedApointInGame;
private void Start() {Score = I;}
public void IncreaseSomething()
//For Decrease of int if player has gotten hit or lost game


that’s all there is to it