For that alignment, it should just be a case of adjusting the latch. You'll need a triple square socket. Can't remember the size. Undo the bolts, slide the latch inwards a bit until you are happy with the alignment, then retighten the bolts.
The top hinge at the front of the door also has some adjustment for sag, if needed.
After adjustment, you might find the door needs a harder slam to shut it until the seals give way a bit.