What is the Process in these PTR sites ?
It is very simple first you have to sign up in any of the PTR site (it's free to join). After signup they will send you the mails every day. You have to open there mails there is a link provided by them all you have to do is click on that link a new window will appear you have to wait 60 secs or more (depending on the site) after that limit of time they will pay you 100$ for reviewing their sites.
They also provides sign up bonus.
Here is the list of some PTR sites :
