Usually every ptc site comes with a number of ads which you have to click on in order to earn the money

Every ad presented in your members area can be clicked only once in 24h. After you‘ve clicked on the ad you will have to wait a number of seconds in order to receive the credits. In the most common situations you will have to wait 30s.

At the end of those 30s, in the top left side of your browser window will appear a small icon which may vary from one PTC to another: a checkmark or a dollar sign… something like in the following picture:

When that kind of icon shows up it means you will receive your money, but there are cases when a red button/sign appears showing that somehow you missed the credit for that ad (this happens sometimes when you have more than one browser windows opened in the same time):

Anyway, to be sure that you will receive the credits for every ad you click, all you have to do is check carefully the TOS for each PTC site.

If you respect their rules you will most certainly receive your credits and also credits from your referrals work.