At what point in your schooling are you? Are you actually in college? If so, I'm not quite sure how you could not know what third person is, so I expect that you do know what it is and you've just never heard the term, if you see what I mean.
It's just when you write without telling things from your point of view; you know, no "I thought" or "I said." If you write "I drove the car," that's first person; if you write, "Llf drove the car," that's third person. Good enough? I imagine you're familiar with what I'm talking about, but if that explanation doesn't ring a bell, let me know and I'll try harder.
Generally, teachers want you to write essays in third person; you avoid writing anything like, "I think," "When I read this," etc. You'd choose instead, "The reader may find," "Some feel that," something like that.
Now, analysis seems pretty self-explanatory. If you don't quite grasp how to write an analytical essay, you probably need to talk to your teacher about what he or she is looking for, get some examples, etc.