We follow the normal rules for badminton but play a single game rather than best of three.
There are plenty of websites that contained detailed information about the rules of badminton. The Badminton Bible is just one and helpfully has a simplified explanation of the rules plus an explanation of the scoring system that we use.
The main thing you need to remember though is that for doubles the court sizes are wide and short for serves only, wide and long for everything else. The singles court size is narrow and long for everything.
If you really do want to read the official rule book, have a browse of the Badminton World Federation site.