Core Script Editing

Hi, I’ve been wanting to make a 2 dimensional platformer game and I already made the 2D Camera.
My main question is how would I get access to this script in game to edit it?

Which script are you trying to edit and why?

Movement script, I’m trying to make it where the user can only move left and right.

Just put a local script with your movement code called “ControlScript” in StarterPlayerScripts

If LocalScript s named “CameraScript” or “ControlScript” are placed within this folder, they will replace the Roblox defaults for those scripts respectively
StarterPlayerScripts | Documentation - Roblox Creator Hub

If you really want to edit the default scripts though you can copy them from your player.PlayerScripts after launching the game.