Go check out the movie 100 girls. Honestly, it's probably the best intro to understanding females in an entertainment form possible. Also, honestly, it's pretty truthful, about all aspects of relationships, but on a more simplified level for teenagers to understand. Probably will score you kudos with your girlfriends if you watch it with them as well.
Have fun with it... I really enjoyed Emmanuelle Chriqui's part in the movie, she fit the character perfectly.