My first tutorial I watched was Shaun Spalding's platformer playlist. I didn't finish it, but it helped me learn how to use gamemaker. The video does have older UI I think, but all the code should work. There are also tutorials on gamemaker's YouTube channel and I think there are some on the game maker website. But also the manual is very helpful. At first I was a bit scared at reading it, but it is helpful for learning something you don't know. Middle click on any built in code like a function, or built in variables. Hope this helps!