how to give parked domain/add domain limit

you are using a reseller account you would need to contact your host


parked domain is an alias of the main domain (share the same content)

add domain uses cpanel subdomain feature and makes a a vitual host container in the apache config file to direct the domain to /public_httml/addondomainfolder/ stand alone
all content in the folder will dispaly as a separate website

EG: http://addondomain.com http://addondomainfolder.maindomain.com http://maindomain.com/addondomainfolder