Hot to define a checkbox in custom field search

[dsharma]

I am adding a custom field in the advanced search - The field is a checkbox by class - I cannot get the field to work correctly i.e. display and accept a checkbox for data - i enter a 1 and it works fine . any help would be appreciated ...thanks
this is what i have....
<input name = 'partner' tabindex='1' size='1' maxlength='1' value = '{...}'>

If i add class = "checkbox" - i get nothing displayed