I imagine that the last sentence is the main idea (please bold it next time). With this plan, I'm guaranteed to have a great time -- as long as I keep my grades up and stay out of trouble.
The author says he will choose good elective courses so my school day is interesting.
I'm going to join clubs so I can meet new friends.
I'm going to fun by attending football games, dances and other social as possible.
All of this paragraph is someone planning so that their day will be rewarding and fun and full -- mostly full.
The setting contributes to the suspense within the text by letting you get a peak of the characters fears, feelings; ect.... while being able to be put in their shoes and switch places with them.
