how to get referrals in ptc sites?

Do you have a blog? You could write about your personal experience with these sites. Post payment proofs if you have any and then add a banner that connects to the site using your referral link. If they don't have a banner, then make one. You might have better luck than with using just a link by itself. Some people intentionally do no sign up through referrals. They'll go and look up the site for themselves themselves and then sign up without one. I don't know if this is because they don't understand the purpose of referrals or what.

No. Because you already know the most-effective way---word of mouth (either In Real Life or on some social-network.)

hi that is simple ,let your refferal link get shorten then put it face book ya. Then you get direct refferals