The conversational tone should sound more like a <em>conversation</em> between two people, rather than just a excerpt from a text.
If you are writing about the Native American Culture, first choose who your audience is- will it be a friend that has no idea about the culture? Maybe a stranger or tourist who is curious on the culture of Native Americans. Whoever it may be, in a conversational tone, try to aim what you write at a single person, like in a private conversation. It will be easier than addressing to a crowd. When I write my answers on here, I like to use a conversational tone aimed at the questioner, as I try to explain the answer and personally help them conquer their problem.
Each paragraph in your essay should be a different topic about Native American culture that you want this curious individual to know. Pretend like you're trying to impress your friends, or someone very important on your knowledge of the Native American Culture- teach the audience about it in a conversation-like tone.
Hope this helps a bit :)
