I found a tutorial for parallax scrolling, and i have code, but i have a new problem.

[Videogamejunkie443]

They do need to repeat!

See, the background position is view_xview[0] * C, where C is a constant between 0 and 1. Thus the background's position is always to the left of the view. So if you don't enable the repetion, the background won't be visible.
By the way, I'm not familiar with Hello Engine but isn't there already an option for parallax scrolling?

As I said, the backgrounds repeat, so I don't need to worry. And if the engine already has a way to make the background scroll like that, I couldn't find the code that let's me do it, so I made a custom object that does just that.