A Background centered on the character

Getting Started Newbie Questions
#1

Hello, I am trying to get the background to move with the character of my game. I set up a different folder to test character movement and I am wondering how I could get the background to sort of center itself on the user. If you’ve played Undertale, I am looking for something similar to that. 

Also, could your code be “compatible” with mine, I mean so that they both work together perfectly. Here are the files and thank you for your support.

#2

Also, is it possible that when doing this there can be parallax scrolling? I am kind of looking for a Mario Platformer kind of effect, despite the fact that there is only one background layer in those games.

#3

Also, is it possible that when doing this there can be parallax scrolling? I am kind of looking for a Mario Platformer kind of effect, despite the fact that there is only one background layer in those games.