"Had" by itself is used to show that you obtained something in the past.
I had a millions dollars, but now I am poor.
I had 1 child, but now I have 4.
I had my keys before I left, but now I can't find them.
"Had to" is used when forced to do something.
I had to go to school. There was no other option.
She had to miss school because she was sick.
Where is John? He had to run to the store to buy some milk.
"Got to" implies doing something you want to do while "had to" implies having no choice
I got to go to the NBA basketball game and see my favorite players!
I had to study; I wish I could have gone!