Read Your Family History to help you prepare for doing such interviews. Be sure to get this information from more than just one person. Use several family members, or use neighbors, friends, relatives, etc. to flesh out the story. Your family history should not try to include every relative that you have ever had, and should not lump many people together with no specific description or characterization. These sources will allow you to see the larger context that your family inhabited, and will help you know what questions to ask.
Families are different, so there is no one approach that is perfect for everyone.
In grading, I will examine several factors. Don't be scared if you don't know much about word processing and computers. This is your opportunity to learn.