Trying to sign up for my children’s free backpacks..

I dont understand this page. Im trying to sign up my child for a free back pack. It states on the paper each child will get one but on here it says sign up to win a back back meaning what? Not all children will get one?? Also im trying to rsvp and all i get is this form is disabled.

Thank you.

Muchas gracias por su ayuda.