I think I know who paid for my summer class.
Who really paid for the summer class?
One of my friend said she'd pay for the summer class
It is nice of your friend to pay for the class. The proper thing to do would be to thank her because she did you a good favor.
I don't think so and I don't appreciate her
Showing gratitude is important when you are given a gift. You should reach out to your friend and thank her for being so gracious.