How do I get something to stay in the same place on-screen..

...let me explain this a little better.

So I'm making my first scrolling proper platformer, and, at a loss of better words to use, I want to put a timer on-screen at all times. Something like in the Mario games, where the timer is stayed put in that one place, at all times, despite the fact that the level scrolls through. How would I achieve this?

I think you need to place it on a separate layer and set it its parallax scrolling values to zero.