Not a bad attempt, although thank you for the tutorial. This may teach someone something in Photoshop.
Although, there is multiple different ways of doing this, and you probably had used the hardest/sloppiest method of them all.
Instead, I would personally have used either one of the optional Lasso tools to select around the person and delete the inverse of my selection.
Or used the Magic Wand tool and selected everything around he person and hit the 'Delete' key on the keyboard.
Those are a couple of other methods you could use that will give you a much cleaner result.
Aside from how you did it, what you did perfectly was organizing your layers correctly. Well done.