Youth Olympic Games qualification process takes place in Chengdu, China. Who will go to Buenos Aires? In 2018 the Youth Olympic Games will take place in Buenos Aires, Argentina from 6-18 October. BMX Freestyle Park is part of it. To qualify your nation for a spot to ride at the YOG, you will need to participate at this year's UCI Urban Cycling World Championships in Chengdu, China (8-12 November).
You will need to be in the age group of 15-18 years old in Chengdu to qualify your nation for a Youth Olympic Games spot. A separate classification will be made for the riders (Male and Female) who fit into the age group of 15-18 years old. The World's will have one Freestyle BMX Park class but a
different classification will be made for those eligible for YOG qualification.
You will need a UCI BMX (freestyle) license to participate at this year's UCI Urban Cycling World Championships and your national federation needs to sign you up before October 27th noon (CET).
This link has more Youth Olympic Games qualification information.