When writing in first person, we say words such as I, we, our, etc. Second person uses words like you, your, etc. If you are trying to write in the third person, you can use words such as he, she, it, they, etc. In this case, instead of using the word "our", you could use the word "one's". It may sound a bit strange, but it can depend on the content of your essay. If you provide more information of specific sentences I'd be happy to clarify. 

For example, instead of saying:

"We must learn from our mistakes."

You would say:

"One must learn from one's mistakes."

I hope that makes sense. Let me know in more detail if that is not helpful.