What is the best way of losing weight?

I like swimming, playing basketball and soccer, tennis, racquetball (with a birdie), and some other sports I like. But, I can't play the sports I like because, I have to work. I might have a vacation soon this month and I'll go back to work on Friday on the first week of August. I also like dancing. I can add the dancing and stretches in my workouts. What are good stretches for exercise too to have workouts at home? I'm not signed up for the YMCA yet, my mom has to get more information to send to the YMCA so we can become members. She still has the form. I can have workouts at home. How long should I exercise? How many workouts should I do? Thank you.