When you begin data extraction, you will see a screen like the one shown in the example. The centre pane shows the general areas of data extraction and allows for quick navigation between each.
Note that the first study you begin DE for in each review will become the 'Review Template'. The tables set up here will be carried over to subsequently started extractions, where they can be individually edited if needed. Only the first reviewer can edit the template; the first reviewer can be changed at any time by clicking "Manage reviewers" on the study's pane Extraction page.