"How did you enjoy ___?" means "Did you enjoy ___?" You answer by describing your opinion of that thing.

For example:

How did you enjoy the massage?

How did you enjoy your trip?

People often ask "How did you enjoy ___?" to someone who they're not very close with. It's not a very personal-sounding question. If you know someone better, you ask "How was ___?":

How was your first day at the new job?