First you need to know what subject, object, and possessive pronouns are.
A subject pronoun is the subject of a verb, also called an action. An example of a subject pronoun is shown on statement 8 of your attachment, "Stu gave"; "Stu" is the subject, and "gave" is the verb, or action, that he is doing. You know it is a subject pronoun because the subject, "Stu," is doing an action, "give." Stu is giving.
An object pronoun is the object of a verb. The object is what is being affected by the action of the verb. Statement 7 is an example of an object pronoun. "Hit" is the action, and "me" is the pronoun, because the action of the stone almost hit "me." So in result of the action, the pronoun was affected, rather than the pronoun caused the action.
A possessive pronoun explains what someone owns. An example includes statement 10. By the word "our" we are expressing ownership, because it is "our" brother.
I hope this made sense and that you can figure out the rest on your own. If you have any other questions, feel free to ask!