Thatz Not Okay: Being a male writing a female in first person

So, I'm working on a new story (this doesn't mean Zero Hour is finished or that I'm done with it, just focusing on other projects).

It's first person, because I'm not good at writing. Also, I'm not good at writing third person. But my current project is about a Maine prep school, and the primary character is female. But because I'm a guy, am I...allowed, for lack of a better term, to write a female character in first person? John Green did.