I have 10 year old son and i'm trying to have a girl what can i do for that to happen?

Same as for males: With embryo selection and transfer at an advanced fertility facility you might accomplish this goal. The expense is high & success is not guaranteed. Regardless of what you may have heard, there is no evidence that a ritual or timing can give you this result. Your chances are the same every pregnancy.

Gender selection: There are approximately 115 boys conceived for every 100 girls. By birth, that ratio is down to 105 boys: 100 girls. Some doctors claim that statistically, you have a better chance of having a girl if sex occurs two or more days before ovulation. The theory is that the timing of intercourse has an effect. Sperm carrying y chromosomes are believed to swim faster but not survive as long.

Trivia fact: Those who use ovulation kits are more apt to have girls.