Wordpress Contact Form 7 Checkboxes Not Working

Ive been trying to add a checkbox to my contact form 7 in worpdress but everytime i add the code it only shows a text box instead of checkbox ive tried everything someone told me i need to add a custom class for checkbox how would i do that and add it to contact form 7 for checkboxes Need Help ASAP thanks.. ive tried this that contact form 7 offers [checkbox checkbox-210 "apple" "books" "cat"] doesnt work