Go to the background and there should be a settings tab somewhere where you can make the background scroll.

I have made a game in GameMaker studio. It is my first proper 'game.'
I have made several games prior, including a Power Toy-like liquid simulation sandbox game, a very very basic top down zombie shooter, and an FPS that I spent about 20 minutes on. My very first game I ever made, without following any tutorials, is on Steam Workshop (but it's pretty bad!).

But I would like to present, my first game that's not terrible bad (but not very good either), DEADMAGEDDON, a top down zombie shooter with multiple campaigns and a survival mode with a shop. I would appreciate any feedback on how I could improve the game.
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=611601564&searchtext=deadmageddon
If you have time, and GameMaker: Studio on Steam, I would love it if you could try it out! Every person who plays my game will bring joy and motivation to me. I will accept all feedback and constructive critisism and will answer any of your pending questions!
BTW, I drew all the death animations myself, I love making them!

I make games sometimes in GameMaker: Studio, and is learning Python at school.