The proof is similar to Another logic proof problem I'm stuck on :( but since there was confusion there, I am proving it using the same Fitch-style proof checker to provide another example:
Note that the goal is a conditional. So, I assume the antecedent of the conditional, ¬Q→¬P, as the beginning of a subproof. I did this on line 2. The indent is how the Fitch-style keeps track of subproofs showing where they start and end.
In that subproof I must derive the consequent, P→R. If I can do that, then I can discharge the subproof and place the derived answer outside the indented subproof. The derivation occurred on line 10. Using conditional introduction, I discharged the assumption and closed the subproof on line 11.
But not only is the goal a conditional, the consequent of the goal, P→R, is also a conditional. So I have to derive its consequent, R, within the subproof. So I make another assumption, P, on line 3 and start a sub-subproof. I try to derive R, which I do on line 9. Then I discharge the assumption on line 3 and close this sub-subproof on line 10.
See the links below for the proof checker and a text describing the rules.
P. D. Magnus, Tim Button with additions by J. Robert Loftis remixed and revised by Aaron Thomas-Bolduc, Richard Zach, forallx Calgary Remix: An Introduction to Formal Logic, Winter 2018.