Max: Do it like this. (The way I am showing you.)
Pat: Do it like that. (The way Max is showing you.)
Use "this" to describe things that are close to you and "that" to describe things that are not close to you.
Max: I want to buy a car like this (one), here.
Pat: What about a car like that (one), over there?
Try, "My professional aim is to be a doctor."
Try, 1st and 2nd, not 1rst and 2n.
All the best.