If you are new to PTC, then you're reading the right stuff! PTC stands for Paid-to-Click or Pay-to-Click which means that you earn money by clicking and viewing ads. The most important thing about the PTC concept is that it's completely free. The sites offer you to buy upgrades and referrals, but that's optional and not needed to earn money.
You're probably wondering how much you can earn. Well, you won't get rich but, with patience, you can earn extra money that you probably need. With time and resolve you could earn per month 100$, 200$ or more, depending on your actions and choices. To do that you'll need referrals, and I tried to explain how to get them here. It's one of the few ways to earn money online that's safe (although it's not always risk-free, we're getting to that part).
There are, of course, scam sites which present themselves as legitimate PTC sites, but don't pay you in the end and disappear. There are signs that a site is a scam, you can check that at the protect yourself from scams post.
Even though some sites pay via Paypal, most sites use only Alerpay to process the payments. Alertpay is a good alternative to Paypal, and you can join by clicking here.
If you want to give PTC a try, visit a "Trusted PTCs" link on the right, or if you want more info check the links on the top of the page, also shown below for your convenience :) :
Reviews
Tutorials
Scams
Payment proofs
Happy clicking :)
PTC Pimp