Each sample is a live signup page. You can join the Samples Members group and take slots by clicking a signup link.
In most signups, you can also untake by clicking on your name. When joining a group it will ask for an email login -
if you do not want to give a real email, please make one up with an ending of "xx", as in firstname.lastname@example.org
(the system will not try to send emails to any ending in "xx").
Your group user will be removed after three hours along with any signup slots you took, everyone will see the sign up slots
you took for that time.