Most women generally ovulate two weeks before the end of their cycle. If you generally have a period every 36 days, you are likely ovulating around cycle length day 22. You want to have sex in the days leading up to ovulation and the day of ovulation.
I also recommend fertility friend. It is a free service and it will teach you about tracking your ovulation and fertility window so you can increase your chances of getting pregnant by having sex at the right times.