How I Had Trouble With Pronouns?

I was doing an assignment about pronouns and was suppose to circle pronouns in the passage according to the text: A pronoun is a word that takes the place of a noun. Pronouns prevent you from using the same noun or noun repetitively. Some pronouns take the place of a single person or thing: I, me, you, he, she, him, her, and it. Other pronouns take the place of plural nouns: we, us, they, and them. I read the examples and it basically talks about the noun then use it again in the same sentence with the following pronoun words: I, me, you, he, she, him, her, and it. Other pronoun words: we, us, they, and them. I was suppose to circle the pronoun words and other pronoun words but instead I circle the nouns that take the place of pronouns thinking it was right and got most of them wrong.
So, I check to see was they correct afterwards and realize how to circle the pronouns.