Installing Brake Light Switch for 1989 Corolla

Hi! My tail & brake lights would not turn off and I was told my brake light switch was bad. I'm not the most mechanically-inclined person, but I thought this might be something even I could do myself.

I was wondering if someone could tell me step by step the proper way to install this switch, plus any do's and don'ts. Also, my battery is dead since the tail lights drained it. Should I jump the car and get the battery charged first?

Thanks!