There should be a button on the right hand side, the symbol is two arrows pointing down. Click on the button and the firewall section should open. If it is empty then there is no configuration made and you would have to create one.
Go to [configure] and select [Interfaces and connections]. Double click on the outside interface. In the window that opens select the tab [Association]. The middle section on the page has [inspect rule], both for inbound and outbound. Normally the firewall is set for outbound so click on the drop down button and select one of the inspection rules.