Hello, I wolud like to know how can I get to Yuanyang from Hekou?

You are suggested to take a train from Hekou North to Mengzi first, which takes about 1h 30 minutes and CNY19.5 for a hard seat.
Then you can take bus 31 to Mengzi Bus Station, take a bus to Gejiu, and the last bus leaves at 19:30.
After you get to Gejiu, you can take a regular bus to YY, and it takes about 1 hour and CNY17.