The imperfect tense denotes that the action in the past did not have a clear beginning or end. You now understand the fundamental distinction between the preterite and the imperfect: The preterite specifies the time and place of an action.
Translated: My friends are Peter and Whitney. They love to make fun things. Peter and Whitney are very sweet. We have been friends for many years. They are brother and sister. We are best friends. Hope this helped!