Once you find a teacher and book a lesson, italki will show you eachothers skype or other contact information. Be sure to put your skype info in your account settings (not your profile itself, the account settings). You will then be able to decide how and when to message eachother. You could even decide to do a different medium by messaging eachother in the italki platform through the scheduled lessons page.

To answer your question:

Language exchange (conversation) does not cost money.  The web interface has a "Language Partner" search.  You can send messages to people.  If they are interested, you both agree on the time and the communication tool (such as Skype).  Sadly, it is somewhat hard to find a conversation partner who wants to practice your language, who is available at suitable times, and who is reliable.

Lessons from teachers and tutors cost money.  You use "Find a Teacher."  You browse the profile information and watch the video for one or more teachers.  You can contact them if you have questions.  You book a lesson.  The lesson includes the teacher's available communication tools (Skype is common) and username.  italki takes the money when you book the lesson.  italki pays the teacher after the lesson finishes.  If there is a problem with the lesson such as the teacher didn't attend, then you can get your money back.

Good luck!

Hello Kimberley, Im Lourdes a Community tutor from Argentina. If you fancy to learn Spanish throught informal conversational practice, please feel free to contact me :) Im running the lessons via Skype. It is a very easy platform to use and we can learn together in a relax atmosphere :) Have a lovely day and many thanks for your time!