To set up a call that happens every other week, begin by creating your call the way you always would. On the first page, enter the subject and agenda, and choose the time of the first call. Then press the green "Recurrence" button to the right of the calendar.

A pop-up will appear which allows you to specify how frequently you want the recurrence to happen.

Choose weekly, and then the frequency -- every 1 week, 2 weeks, and so on.
When you're finished press OK, and continue creating the call as you always have.