check agreement

I am looking for help with the contest gallery plug in. On the “edit upload form” we have a option to choose “check agreement” I cannot seem to get this to work? I would like to use it as a checkbox which must be checked before they can post pictures. I would like it to be used by visitors to check the box if they agree to the site policies. I have tired inserting the page my polices are on but nothing happens. I also don’t see where I can put in the words for example” by checking the box you agree to our terms of use” Does anyone have any videos or the step by step instructions if this is possible?