Used to or Use to?

The website 5MinuteEnglish.com explains that when we add USE TO + verb we are using it as a verb form. Perhaps an auxiliary? Here's how they explain it:

Used as a verb. Use to + verb is a regular verb and means something that happened but doesn't happen any more. It uses -ed to show past tense. But since it always means something that happened in the past, it should always use past tense. For example- I used to go to school in Paris.(I went to school there before, but now I don't.) Or, When Joshua was a child, he used to climb trees. (Now he doesn't climb trees.)

Remember, we always use this word when talking about the past. So when do you use use to without the d at the end? When the base form of the verb is used. Look at these examples- She didn't use to swim before noon. (Now she does swim before noon.) Or Did your father use to ride a horse? In these cases the past tense is shown with the did and didn't.

5minuteenglish.com