How can I Keep my hair accessory still?

I'm having athletics day tomorrow and my colour is pink and i brought one of these hair accessories;

http://tinyurl.com/2hg4yj

http://tinyurl.com/2ezfgq

everytime i put it on.. the thing kind of goes up and makes my hair boof. how can i keep it still? thanks . any help or suggestions or tips appreciated. :)

How can I Keep my hair accessory still?

bobby pins that matches the color of it so they blend in :]

How can I Keep my hair accessory still?

I can't see the pic so idk