Around all casino site offer referral program. There are many popular gambling site available on this forum. You should check all site yourself and make your own decision which casino you will use for earn referral Commission. But Beware of scam casinos.
Your post is enough to make a laugh. The person is asking it as s/he do not want to use all and also may not be able to know which is legit site and which is scam. That's why Op is asking the question to get the solution easily without doing any effort regarding this.