There are various ways you can use italki, but although the website itself is free, it is mainly a marketplace for matching up students with professional, paid teachers who give you individual lessons via videocalls (often Skype).
italki handles scheduling and payments, and exercises some quality control (they hold your payment until after the session is over, and if anything goes wrong you can get your money back, and so forth). I've paid for lessons with two different teachers and found them both to be excellent--skillful and professional.
But basically the way you use italki is that you buy individual lessons from individual teachers.
The teachers do not work for italki.
You can also use italki to find "language partners," people who are interested in learning your language and helping you learn theirs. This is just a communications service. It doesn't cost anything and you don't pay your language partner... and nothing is guaranteed. Some language partners are helpful, some are not. Some are sincerely interested in a language exchange, and unfortunately some are not. You are agreeing to meet strangers on the Internet and talk to them.
hey Hello, I'm a new member. i wanna I'd like to know if i'm gonna I have to pay for the lessons or not?
If you want proper lessons, then yes you need to buy ITC (italki credits) and pay for the lessons. Your other option is to find a "language partner" from the community, and make a fair exchange of language.