How to make an AI like slender ?

Hello, is there any script that make the enemy (like slender) follow the player after he pick-up a page (item) and the more items the player pick, the more closer the enemy will be... Actually I want an enemy that does the EXACTLY same thing as Slender does... (Following as the player pick the pages, killing if is too close, playing a sound when first seen by the player...) as I don't know almost nothing of Unity (just the basic), I would be glad if you teach me how to use the script in the enemy and in the player.

PS: I already created all the map and did my own models, I created the flashlight and some keys to some doors, what I need to finish my game is "just" the enemy and the pages.