1) He had breakfast today = He didn't have breakfast today
2) He has had breakfast today = he hasn't had breakfast today
1 is the past simple and 2 is the present perfect.
It's the same for the other examples.
To form the negative we add the aux "do" with "not" (didn't) where there is no aux in the affirmative statement, and we slot "not" ('t) between the aux and main verb where there is (i.e. with a tense such as the present perfect).
I am not a teacher.
Student or Learner