I am totally new to horse racing so I need to ask if I understand something correctly about wagering.

Yesterday I placed a wager on the Oaks/Derby race. On horse #8 to show in the Oaks. Which I thought also carried over to the Derby race since it was a Double. #8 won today. Does that mean I won the double payout?

Any advice would be greatly appreciated. I don't know if I won anything worthwhile or not.