This script will check that the user has checked the agree box in your form/contract etc.
<The Form >
<legend>Agree Box</legend><form name="myForm" action="" onsubmit="return agreeBox(this)">
I agree that all information entered is true at time of submitting.
<input type="checkbox" name="boxAgree">
<input type="submit" value="Submit">
<!-- Hide from old browsers
if (myForm.boxAgree.checked == false )
alert('Please verify that you agree that all information entered is true at time of submitting.');
Please let me know if this script was helpful to you.