Taking my profile as an example, you will find price and time for lessons. For example, if you're interested in an hour of tutoring, it will cost $8usd. Or half and hour, $5usd. You choose which one fits your necessities as a student.
Then you choose the day and hour you want to take the lesson, and that day we connect trough skype, which is what i use, and we have a conversation about anything you're interested in, or, you can tell me if you can to practice anything in particular.
Then, when time's over, we give feedback to eachother, and that's it.
If you have any other question feel free to ask me.