What motivates Human beings?
How is abberant behaviour determined?
What is the norm?
Who knows the hearts of evil men?
How do children learn?
All these are good introductions to Psychology, so seek out some answers.
What questions about human behavior concern you and/or the two others in your group? How to do well in college? How to study? Developing friendships and/or romantic relationships? Gender differences in behavior? How to lead a discussion?
Here are some articles that might give you ideas and/or help you in your presentation.
I hope this helps a little more. Thanks for asking.