As you can see in the Feature / Platform Matrix, the entry level models have a number of features that are only available using the Command Line Interface (CLI), rather than appearing in the GUI.
You can use FortiExplorer or terminal emulation software to access the CLI. The CLI can also be assessed from within the GUI, by going to the Dashboard and using the CLI Console widget. If the console does not appear in the dashboard, select Widget, then select CLI Console. The console can also be accessed by using the drop-down menu in the top right of the page, where your account's user name is shown.
You can also open the CLI console so that it automatically opens to the object you wish to configure. For example, to edit a firewall policy, right-click on the policy in the list (Policy & Objects > IPv4 Policy) and select Edit in CLI. The CLI console will appear, with the commands to access this part of the configuration added automatically.
Once you have access to the CLI, you can enter instructions for specific tasks that can be found throughout the FortiOS Handbook. You can also refer to the CLI Reference for a list of the available commands.